CSY/reowolf Changeset - d23aebafc979 · Centrum Wiskunde & Informatica (CWI)

Changeset - d23aebafc979

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MH - 4 years ago 2021-12-14 17:08:09
contact@maxhenger.nl

Initial TypeTable rewrite to support Tuple size/alignment computations

7 files changed with 628 insertions and 429 deletions:

src/protocol/ast.rs

src/protocol/eval/executor.rs

src/protocol/mod.rs

src/protocol/parser/pass_typing.rs

src/protocol/parser/type_table.rs

537

366

src/protocol/tests/parser_monomorphs.rs

src/protocol/tests/utils.rs

0 comments (0 inline, 0 general)

src/protocol/ast.rs

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 use std::fmt;
 use std::fmt::{Debug, Display, Formatter};
 use std::ops::{Index, IndexMut};
 use super::arena::{Arena, Id};
 use crate::collections::StringRef;
 use crate::protocol::input_source::InputSpan;
 /// Helper macro that defines a type alias for a AST element ID. In this case
 /// only used to alias the `Id<T>` types.
 macro_rules! define_aliased_ast_id {
     // Variant where we just defined the alias, without any indexing
     ($name:ident, $parent:ty) => {
         pub type $name = $parent;
     };
     // Variant where we define the type, and the Index and IndexMut traits
+    (
         $name:ident, $parent:ty,
         index($indexed_type:ty, $indexed_arena:ident)
     ) => {
         define_aliased_ast_id!($name, $parent);
         impl Index<$name> for Heap {
             type Output = $indexed_type;
             fn index(&self, index: $name) -> &Self::Output {
                 &self.$indexed_arena[index]
+            }
+        }
         impl IndexMut<$name> for Heap {
             fn index_mut(&mut self, index: $name) -> &mut Self::Output {
                 &mut self.$indexed_arena[index]
+            }
+        }
     };
     // Variant where we define type, Index(Mut) traits and an allocation function
+    (
         $name:ident, $parent:ty,
         index($indexed_type:ty, $indexed_arena:ident),
         alloc($fn_name:ident)
     ) => {
         define_aliased_ast_id!($name, $parent, index($indexed_type, $indexed_arena));
         impl Heap {
             pub fn $fn_name(&mut self, f: impl FnOnce($name) -> $indexed_type) -> $name {
                 self.$indexed_arena.alloc_with_id(|id| f(id))
+            }
+        }
     };
+}
 /// Helper macro that defines a wrapper type for a particular variant of an AST
 /// element ID. Only used to define single-wrapping IDs.
 macro_rules! define_new_ast_id {
     // Variant where we just defined the new type, without any indexing
     ($name:ident, $parent:ty) => {
         #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
         pub struct $name (pub(crate) $parent);
         #[allow(dead_code)]
         impl $name {
             pub(crate) fn new_invalid() -> Self     { Self(<$parent>::new_invalid()) }
             pub(crate) fn is_invalid(&self) -> bool { self.0.is_invalid() }
             pub fn upcast(self) -> $parent          { self.0 }
+        }
     };
     // Variant where we define the type, and the Index and IndexMut traits
+    (
         $name:ident, $parent:ty,
         index($indexed_type:ty, $wrapper_type:path, $indexed_arena:ident)
     ) => {
         define_new_ast_id!($name, $parent);
         impl Index<$name> for Heap {
             type Output = $indexed_type;
             fn index(&self, index: $name) -> &Self::Output {
                 if let $wrapper_type(v) = &self.$indexed_arena[index.0] {
+                    v
                 } else {
                     unreachable!()
+                }
+            }
+        }
         impl IndexMut<$name> for Heap {
             fn index_mut(&mut self, index: $name) -> &mut Self::Output {
                 if let $wrapper_type(v) = &mut self.$indexed_arena[index.0] {
+                    v
                 } else {
                     unreachable!()
+                }
+            }
+        }
     };
     // Variant where we define the type, the Index and IndexMut traits, and an allocation function
+    (
         $name:ident, $parent:ty,
         index($indexed_type:ty, $wrapper_type:path, $indexed_arena:ident),
         alloc($fn_name:ident)
     ) => {
         define_new_ast_id!($name, $parent, index($indexed_type, $wrapper_type, $indexed_arena));
         impl Heap {
             pub fn $fn_name(&mut self, f: impl FnOnce($name) -> $indexed_type) -> $name {
                 $name(
                     self.$indexed_arena.alloc_with_id(|id| {
                         $wrapper_type(f($name(id)))
                     })
+                )
+            }
+        }
+    }
+}
 define_aliased_ast_id!(RootId, Id<Root>, index(Root, protocol_descriptions), alloc(alloc_protocol_description));
 define_aliased_ast_id!(PragmaId, Id<Pragma>, index(Pragma, pragmas), alloc(alloc_pragma));
 define_aliased_ast_id!(ImportId, Id<Import>, index(Import, imports), alloc(alloc_import));
 define_aliased_ast_id!(VariableId, Id<Variable>, index(Variable, variables), alloc(alloc_variable));
 define_aliased_ast_id!(DefinitionId, Id<Definition>, index(Definition, definitions));
 define_new_ast_id!(StructDefinitionId, DefinitionId, index(StructDefinition, Definition::Struct, definitions), alloc(alloc_struct_definition));
 define_new_ast_id!(EnumDefinitionId, DefinitionId, index(EnumDefinition, Definition::Enum, definitions), alloc(alloc_enum_definition));
 define_new_ast_id!(UnionDefinitionId, DefinitionId, index(UnionDefinition, Definition::Union, definitions), alloc(alloc_union_definition));
 define_new_ast_id!(ComponentDefinitionId, DefinitionId, index(ComponentDefinition, Definition::Component, definitions), alloc(alloc_component_definition));
 define_new_ast_id!(FunctionDefinitionId, DefinitionId, index(FunctionDefinition, Definition::Function, definitions), alloc(alloc_function_definition));
 define_aliased_ast_id!(StatementId, Id<Statement>, index(Statement, statements));
 define_new_ast_id!(BlockStatementId, StatementId, index(BlockStatement, Statement::Block, statements), alloc(alloc_block_statement));
 define_new_ast_id!(EndBlockStatementId, StatementId, index(EndBlockStatement, Statement::EndBlock, statements), alloc(alloc_end_block_statement));
 define_new_ast_id!(LocalStatementId, StatementId, index(LocalStatement, Statement::Local, statements));
 define_new_ast_id!(MemoryStatementId, LocalStatementId);
 define_new_ast_id!(ChannelStatementId, LocalStatementId);
 define_new_ast_id!(LabeledStatementId, StatementId, index(LabeledStatement, Statement::Labeled, statements), alloc(alloc_labeled_statement));
 define_new_ast_id!(IfStatementId, StatementId, index(IfStatement, Statement::If, statements), alloc(alloc_if_statement));
 define_new_ast_id!(EndIfStatementId, StatementId, index(EndIfStatement, Statement::EndIf, statements), alloc(alloc_end_if_statement));
 define_new_ast_id!(WhileStatementId, StatementId, index(WhileStatement, Statement::While, statements), alloc(alloc_while_statement));
 define_new_ast_id!(EndWhileStatementId, StatementId, index(EndWhileStatement, Statement::EndWhile, statements), alloc(alloc_end_while_statement));
 define_new_ast_id!(BreakStatementId, StatementId, index(BreakStatement, Statement::Break, statements), alloc(alloc_break_statement));
 define_new_ast_id!(ContinueStatementId, StatementId, index(ContinueStatement, Statement::Continue, statements), alloc(alloc_continue_statement));
 define_new_ast_id!(SynchronousStatementId, StatementId, index(SynchronousStatement, Statement::Synchronous, statements), alloc(alloc_synchronous_statement));
 define_new_ast_id!(EndSynchronousStatementId, StatementId, index(EndSynchronousStatement, Statement::EndSynchronous, statements), alloc(alloc_end_synchronous_statement));
 define_new_ast_id!(ForkStatementId, StatementId, index(ForkStatement, Statement::Fork, statements), alloc(alloc_fork_statement));
 define_new_ast_id!(EndForkStatementId, StatementId, index(EndForkStatement, Statement::EndFork, statements), alloc(alloc_end_fork_statement));
 define_new_ast_id!(ReturnStatementId, StatementId, index(ReturnStatement, Statement::Return, statements), alloc(alloc_return_statement));
 define_new_ast_id!(GotoStatementId, StatementId, index(GotoStatement, Statement::Goto, statements), alloc(alloc_goto_statement));
 define_new_ast_id!(NewStatementId, StatementId, index(NewStatement, Statement::New, statements), alloc(alloc_new_statement));
 define_new_ast_id!(ExpressionStatementId, StatementId, index(ExpressionStatement, Statement::Expression, statements), alloc(alloc_expression_statement));
 define_aliased_ast_id!(ExpressionId, Id<Expression>, index(Expression, expressions));
 define_new_ast_id!(AssignmentExpressionId, ExpressionId, index(AssignmentExpression, Expression::Assignment, expressions), alloc(alloc_assignment_expression));
 define_new_ast_id!(BindingExpressionId, ExpressionId, index(BindingExpression, Expression::Binding, expressions), alloc(alloc_binding_expression));
 define_new_ast_id!(ConditionalExpressionId, ExpressionId, index(ConditionalExpression, Expression::Conditional, expressions), alloc(alloc_conditional_expression));
 define_new_ast_id!(BinaryExpressionId, ExpressionId, index(BinaryExpression, Expression::Binary, expressions), alloc(alloc_binary_expression));
 define_new_ast_id!(UnaryExpressionId, ExpressionId, index(UnaryExpression, Expression::Unary, expressions), alloc(alloc_unary_expression));
 define_new_ast_id!(IndexingExpressionId, ExpressionId, index(IndexingExpression, Expression::Indexing, expressions), alloc(alloc_indexing_expression));
 define_new_ast_id!(SlicingExpressionId, ExpressionId, index(SlicingExpression, Expression::Slicing, expressions), alloc(alloc_slicing_expression));
 define_new_ast_id!(SelectExpressionId, ExpressionId, index(SelectExpression, Expression::Select, expressions), alloc(alloc_select_expression));
 define_new_ast_id!(LiteralExpressionId, ExpressionId, index(LiteralExpression, Expression::Literal, expressions), alloc(alloc_literal_expression));
 define_new_ast_id!(CastExpressionId, ExpressionId, index(CastExpression, Expression::Cast, expressions), alloc(alloc_cast_expression));
 define_new_ast_id!(CallExpressionId, ExpressionId, index(CallExpression, Expression::Call, expressions), alloc(alloc_call_expression));
 define_new_ast_id!(VariableExpressionId, ExpressionId, index(VariableExpression, Expression::Variable, expressions), alloc(alloc_variable_expression));
 #[derive(Debug)]
 pub struct Heap {
     // Root arena, contains the entry point for different modules. Each root
     // contains lists of IDs that correspond to the other arenas.
     pub(crate) protocol_descriptions: Arena<Root>,
     // Contents of a file, these are the elements the `Root` elements refer to
     pragmas: Arena<Pragma>,
     pub(crate) imports: Arena<Import>,
     pub(crate) variables: Arena<Variable>,
     pub(crate) definitions: Arena<Definition>,
     pub(crate) statements: Arena<Statement>,
     pub(crate) expressions: Arena<Expression>,
+}
 impl Heap {
     pub fn new() -> Heap {
         Heap {
             // string_alloc: StringAllocator::new(),
             protocol_descriptions: Arena::new(),
             pragmas: Arena::new(),
             imports: Arena::new(),
             variables: Arena::new(),
             definitions: Arena::new(),
             statements: Arena::new(),
             expressions: Arena::new(),
+        }
+    }
     pub fn alloc_memory_statement(
         &mut self,
         f: impl FnOnce(MemoryStatementId) -> MemoryStatement,
     ) -> MemoryStatementId {
         MemoryStatementId(LocalStatementId(self.statements.alloc_with_id(|id| {
             Statement::Local(LocalStatement::Memory(
                 f(MemoryStatementId(LocalStatementId(id)))
             ))
         })))
+    }
     pub fn alloc_channel_statement(
         &mut self,
         f: impl FnOnce(ChannelStatementId) -> ChannelStatement,
     ) -> ChannelStatementId {
         ChannelStatementId(LocalStatementId(self.statements.alloc_with_id(|id| {
             Statement::Local(LocalStatement::Channel(
                 f(ChannelStatementId(LocalStatementId(id)))
             ))
         })))
+    }
+}
 impl Index<MemoryStatementId> for Heap {
     type Output = MemoryStatement;
     fn index(&self, index: MemoryStatementId) -> &Self::Output {
         &self.statements[index.0.0].as_memory()
+    }
+}
 impl Index<ChannelStatementId> for Heap {
     type Output = ChannelStatement;
     fn index(&self, index: ChannelStatementId) -> &Self::Output {
         &self.statements[index.0.0].as_channel()
+    }
+}
 #[derive(Debug, Clone)]
 pub struct Root {
     pub this: RootId,
     // Phase 1: parser
     // pub position: InputPosition,
     pub pragmas: Vec<PragmaId>,
     pub imports: Vec<ImportId>,
     pub definitions: Vec<DefinitionId>,
+}
 impl Root {
     pub fn get_definition_ident(&self, h: &Heap, id: &[u8]) -> Option<DefinitionId> {
         for &def in self.definitions.iter() {
             if h[def].identifier().value.as_bytes() == id {
                 return Some(def);
+            }
+        }
         None
+    }
+}
 #[derive(Debug, Clone)]
 pub enum Pragma {
     Version(PragmaVersion),
     Module(PragmaModule),
+}
 impl Pragma {
     pub(crate) fn as_module(&self) -> &PragmaModule {
         match self {
             Pragma::Module(pragma) => pragma,
             _ => unreachable!("Tried to obtain {:?} as PragmaModule", self),
+        }
+    }
+}
 #[derive(Debug, Clone)]
 pub struct PragmaVersion {
     pub this: PragmaId,
     // Phase 1: parser
     pub span: InputSpan, // of full pragma
     pub version: u64,
+}
 #[derive(Debug, Clone)]
 pub struct PragmaModule {
     pub this: PragmaId,
     // Phase 1: parser
     pub span: InputSpan, // of full pragma
     pub value: Identifier,
+}
 #[derive(Debug, Clone)]
 pub enum Import {
     Module(ImportModule),
     Symbols(ImportSymbols)
+}
 impl Import {
     pub(crate) fn span(&self) -> InputSpan {
         match self {
             Import::Module(v) => v.span,
             Import::Symbols(v) => v.span,
+        }
+    }
     pub(crate) fn as_module(&self) -> &ImportModule {
         match self {
             Import::Module(m) => m,
             _ => unreachable!("Unable to cast 'Import' to 'ImportModule'")
+        }
+    }
     pub(crate) fn as_symbols(&self) -> &ImportSymbols {
         match self {
             Import::Symbols(m) => m,
             _ => unreachable!("Unable to cast 'Import' to 'ImportSymbols'")
+        }
+    }
     pub(crate) fn as_symbols_mut(&mut self) -> &mut ImportSymbols {
         match self {
             Import::Symbols(m) => m,
             _ => unreachable!("Unable to cast 'Import' to 'ImportSymbols'")
+        }
+    }
+}
 #[derive(Debug, Clone)]
 pub struct ImportModule {
     pub this: ImportId,
     // Phase 1: parser
     pub span: InputSpan,
     pub module: Identifier,
     pub alias: Identifier,
     pub module_id: RootId,
+}
 #[derive(Debug, Clone)]
 pub struct AliasedSymbol {
     pub name: Identifier,
     pub alias: Option<Identifier>,
     pub definition_id: DefinitionId,
+}
 #[derive(Debug, Clone)]
 pub struct ImportSymbols {
     pub this: ImportId,
     // Phase 1: parser
     pub span: InputSpan,
     pub module: Identifier,
     pub module_id: RootId,
     pub symbols: Vec<AliasedSymbol>,
+}
 #[derive(Debug, Clone)]
 pub struct Identifier {
     pub span: InputSpan,
     pub value: StringRef<'static>,
+}
 impl PartialEq for Identifier {
     fn eq(&self, other: &Self) -> bool {
         return self.value == other.value
+    }
+}
 impl Display for Identifier {
     fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
         write!(f, "{}", self.value.as_str())
+    }
+}
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub enum ParserTypeVariant {
     // Special builtin, only usable by the compiler and not constructable by the
     // programmer
     Void,
     InputOrOutput,
     ArrayLike,
     IntegerLike,
     // Basic builtin
     Message,
     Bool,
     UInt8, UInt16, UInt32, UInt64,
     SInt8, SInt16, SInt32, SInt64,
     Character, String,
     // Literals (need to get concrete builtin type during typechecking)
     IntegerLiteral,
     // Marker for inference
     Inferred,
     // Builtins expecting one subsequent type
     Array,
     Input,
     Output,
     // Tuple: expecting any number of elements. Note that the parser type can
     // have one-valued tuples, these will be filtered out later during type
     // checking.
     Tuple(u32), // u32 = number of subsequent types
     // User-defined types
     PolymorphicArgument(DefinitionId, u32), // u32 = index into polymorphic variables
     Definition(DefinitionId, u32), // u32 = number of subsequent types in the type tree.
+}
 impl ParserTypeVariant {
     pub(crate) fn num_embedded(&self) -> usize {
         use ParserTypeVariant::*;
         match self {
             Void | IntegerLike |
             Message | Bool |
             UInt8 | UInt16 | UInt32 | UInt64 |
             SInt8 | SInt16 | SInt32 | SInt64 |
             Character | String | IntegerLiteral |
             Inferred | PolymorphicArgument(_, _) =>
 ,
             ArrayLike | InputOrOutput | Array | Input | Output =>
 ,
             Definition(_, num) | Tuple(num) => *num as usize,
+        }
+    }
+}
 /// ParserTypeElement is an element of the type tree. An element may be
 /// implicit, meaning that the user didn't specify the type, but it was set by
 /// the compiler.
 #[derive(Debug, Clone)]
 pub struct ParserTypeElement {
     pub element_span: InputSpan, // span of this element, not including the child types
     pub variant: ParserTypeVariant,
+}
 /// ParserType is a specification of a type during the parsing phase and initial
 /// linker/validator phase of the compilation process. These types may be
 /// (partially) inferred or represent literals (e.g. a integer whose bytesize is
 /// not yet determined).
 ///
 /// Its contents are the depth-first serialization of the type tree. Each node
 /// is a type that may accept polymorphic arguments. The polymorphic arguments
 /// are then the children of the node.
 #[derive(Debug, Clone)]
 pub struct ParserType {
     pub elements: Vec<ParserTypeElement>,
     pub full_span: InputSpan,
+}
 impl ParserType {
     pub(crate) fn iter_embedded(&self, parent_idx: usize) -> ParserTypeIter {
         ParserTypeIter::new(&self.elements, parent_idx)
+    }
+}
 /// Iterator over the embedded elements of a specific element.
 pub struct ParserTypeIter<'a> {
     pub elements: &'a [ParserTypeElement],
     pub cur_embedded_idx: usize,
+}
 impl<'a> ParserTypeIter<'a> {
     fn new(elements: &'a [ParserTypeElement], parent_idx: usize) -> Self {
         debug_assert!(parent_idx < elements.len(), "parent index exceeds number of elements in ParserType");
         if elements[0].variant.num_embedded() == 0 {
             // Parent element does not have any embedded types, place
             // `cur_embedded_idx` at end so we will always return `None`
             Self{ elements, cur_embedded_idx: elements.len() }
         } else {
             // Parent element has an embedded type
             Self{ elements, cur_embedded_idx: parent_idx + 1 }
+        }
+    }
+}
 impl<'a> Iterator for ParserTypeIter<'a> {
     type Item = &'a [ParserTypeElement];
     fn next(&mut self) -> Option<Self::Item> {
         let elements_len = self.elements.len();
         if self.cur_embedded_idx >= elements_len {
             return None;
+        }
         // Seek to the end of the subtree
         let mut depth = 1;
         let start_element = self.cur_embedded_idx;
         while self.cur_embedded_idx < elements_len {
             let cur_element = &self.elements[self.cur_embedded_idx];
             let depth_change = cur_element.variant.num_embedded() as i32 - 1;
             depth += depth_change;
             debug_assert!(depth >= 0, "illegally constructed ParserType: {:?}", self.elements);
             self.cur_embedded_idx += 1;
             if depth == 0 {
                 break;
+            }
+        }
         debug_assert!(depth == 0, "illegally constructed ParserType: {:?}", self.elements);
         return Some(&self.elements[start_element..self.cur_embedded_idx]);
+    }
+}
 /// ConcreteType is the representation of a type after the type inference and
 /// checker is finished. These are fully typed.
 #[derive(Debug, Clone, Copy, Eq, PartialEq)]
+#[derive(Debug, Clone, Copy, Eq, PartialEq, Hash)]
 pub enum ConcreteTypePart {
     // Special types (cannot be explicitly constructed by the programmer)
     Void,
     // Builtin types without nested types
     Message,
     Bool,
     UInt8, UInt16, UInt32, UInt64,
     SInt8, SInt16, SInt32, SInt64,
     Character, String,
     // Builtin types with one nested type
     Array,
     Slice,
     Input,
     Output,
     // Tuple: variable number of nested types, will never be 1
     Tuple(u32),
     // User defined type with any number of nested types
     Instance(DefinitionId, u32),    // instance of data type
     Function(DefinitionId, u32),    // instance of function
     Component(DefinitionId, u32),   // instance of a connector
+}
 impl ConcreteTypePart {
     fn num_embedded(&self) -> u32 {
+    pub(crate) fn num_embedded(&self) -> u32 {
         use ConcreteTypePart::*;
         match self {
             Void | Message | Bool |
             UInt8 | UInt16 | UInt32 | UInt64 |
             SInt8 | SInt16 | SInt32 | SInt64 |
             Character | String =>
 ,
             Array | Slice | Input | Output =>
 ,
             Tuple(num_embedded) => *num_embedded,
             Instance(_, num_embedded) => *num_embedded,
             Function(_, num_embedded) => *num_embedded,
             Component(_, num_embedded) => *num_embedded,
+        }
+    }
+}
 #[derive(Debug, Clone, Eq, PartialEq)]
 pub struct ConcreteType {
     pub(crate) parts: Vec<ConcreteTypePart>
+}
 impl Default for ConcreteType {
     fn default() -> Self {
         Self{ parts: Vec::new() }
+    }
+}
 impl ConcreteType {
     /// Returns an iterator over the subtrees that are type arguments (e.g. an
     /// array element's type, or a polymorphic type's arguments) to the
     /// provided parent type (specified by its index in the `parts` array).
     pub(crate) fn embedded_iter(&self, parent_part_idx: usize) -> ConcreteTypeIter {
         return ConcreteTypeIter::new(&self.parts, parent_part_idx);
+    }
     /// Construct a human-readable name for the type. Because this performs
     /// a string allocation don't use it for anything else then displaying the
     /// type to the user.
     pub(crate) fn display_name(&self, heap: &Heap) -> String {
         return Self::type_parts_display_name(self.parts.as_slice(), heap);
+    }
     // --- Utilities that operate on slice of parts
     /// Given the starting position of a type tree, determine the exclusive
     /// ending index.
     pub(crate) fn type_parts_subtree_end_idx(parts: &[ConcreteTypePart], start_idx: usize) -> usize {
         let mut depth = 1;
         let num_parts = parts.len();
         debug_assert!(start_idx < num_parts);
         for part_idx in start_idx..parts.len() {
             let depth_change = parts[part_idx].num_embedded() as i32 - 1;
             depth += depth_change;
             debug_assert!(depth >= 0);
             if depth == 0 {
                 return part_idx + 1;
+            }
+        }
         debug_assert!(false, "incorrectly constructed ConcreteType instance");
         return 0;
+    }
     /// Produces a human-readable representation of the concrete type parts
     fn type_parts_display_name(parts: &[ConcreteTypePart], heap: &Heap) -> String {
         let mut name = String::with_capacity(128);
         let _final_idx = Self::render_type_part_at(parts, heap, 0, &mut name);
         debug_assert_eq!(_final_idx, parts.len());
         return name;
+    }
     /// Produces a human-readable representation of a single type part. Lower
     /// level utility for `type_parts_display_name`.
     fn render_type_part_at(parts: &[ConcreteTypePart], heap: &Heap, mut idx: usize, target: &mut String) -> usize {
         use ConcreteTypePart as CTP;
         use crate::protocol::parser::token_parsing::*;
         let cur_idx = idx;
         idx += 1; // increment by 1, because it always happens
         match parts[cur_idx] {
             CTP::Void => { target.push_str("void"); },
             CTP::Message => { target.push_str(KW_TYPE_MESSAGE_STR); },
             CTP::Bool => { target.push_str(KW_TYPE_BOOL_STR); },
             CTP::UInt8 => { target.push_str(KW_TYPE_UINT8_STR); },
             CTP::UInt16 => { target.push_str(KW_TYPE_UINT16_STR); },
             CTP::UInt32 => { target.push_str(KW_TYPE_UINT32_STR); },
             CTP::UInt64 => { target.push_str(KW_TYPE_UINT64_STR); },
             CTP::SInt8 => { target.push_str(KW_TYPE_SINT8_STR); },
             CTP::SInt16 => { target.push_str(KW_TYPE_SINT16_STR); },
             CTP::SInt32 => { target.push_str(KW_TYPE_SINT32_STR); },
             CTP::SInt64 => { target.push_str(KW_TYPE_SINT64_STR); },
             CTP::Character => { target.push_str(KW_TYPE_CHAR_STR); },
             CTP::String => { target.push_str(KW_TYPE_STRING_STR); },
             CTP::Array | CTP::Slice => {
                 idx = Self::render_type_part_at(parts, heap, idx, target);
                 target.push_str("[]");
             },
             CTP::Input => {
                 target.push_str(KW_TYPE_IN_PORT_STR);
                 target.push('<');
                 idx = Self::render_type_part_at(parts, heap, idx, target);
                 target.push('>');
             },
             CTP::Output => {
                 target.push_str(KW_TYPE_OUT_PORT_STR);
                 target.push('<');
                 idx = Self::render_type_part_at(parts, heap, idx, target);
                 target.push('>');
             },
             CTP::Tuple(num_parts) => {
                 target.push('(');
                 if num_parts != 0 {
                     idx = Self::render_type_part_at(parts, heap, idx, target);
                     for _ in 1..num_parts {
                         target.push(',');
                         idx = Self::render_type_part_at(parts, heap, idx, target);
+                    }
+                }
                 target.push(')');
             },
             CTP::Instance(definition_id, num_poly_args) |
             CTP::Function(definition_id, num_poly_args) |
             CTP::Component(definition_id, num_poly_args) => {
                 let definition = &heap[definition_id];
                 target.push_str(definition.identifier().value.as_str());
                 if num_poly_args != 0 {
                     target.push('<');
                     for poly_arg_idx in 0..num_poly_args {
                         if poly_arg_idx != 0 {
                             target.push(',');
+                        }
                         idx = Self::render_type_part_at(parts, heap, idx, target);
+                    }
                     target.push('>');
+                }
+            }
+        }
         idx
+    }
+}
 #[derive(Debug)]
 pub struct ConcreteTypeIter<'a> {
     parts: &'a [ConcreteTypePart],
     idx_embedded: u32,
     num_embedded: u32,
     part_idx: usize,
+}
 impl<'a> ConcreteTypeIter<'a> {
     pub(crate) fn new(parts: &'a[ConcreteTypePart], parent_idx: usize) -> Self {
         let num_embedded = parts[parent_idx].num_embedded();
         return ConcreteTypeIter{
             parts,
             idx_embedded: 0,
             num_embedded,
             part_idx: parent_idx + 1,
+        }
+    }
+}
 impl<'a> Iterator for ConcreteTypeIter<'a> {
     type Item = &'a [ConcreteTypePart];
     fn next(&mut self) -> Option<Self::Item> {
         if self.idx_embedded == self.num_embedded {
             return None;
+        }
         // Retrieve the subtree of interest
         let start_idx = self.part_idx;
         let end_idx = ConcreteType::type_parts_subtree_end_idx(&self.parts, start_idx);
         self.idx_embedded += 1;
         self.part_idx = end_idx;
         return Some(&self.parts[start_idx..end_idx]);
+    }
+}
 #[derive(Debug, Clone, Copy)]
 pub enum Scope {
     Definition(DefinitionId),
     Regular(BlockStatementId),
     Synchronous((SynchronousStatementId, BlockStatementId)),
+}
 impl Scope {
     pub fn is_block(&self) -> bool {
         match &self {
             Scope::Definition(_) => false,
             Scope::Regular(_) => true,
             Scope::Synchronous(_) => true,
+        }
+    }
     pub fn to_block(&self) -> BlockStatementId {
         match &self {
             Scope::Regular(id) => *id,
             Scope::Synchronous((_, id)) => *id,
             _ => panic!("unable to get BlockStatement from Scope")
+        }
+    }
+}
 /// `ScopeNode` is a helper that links scopes in two directions. It doesn't
 /// actually contain any information associated with the scope, this may be
 /// found on the AST elements that `Scope` points to.
 #[derive(Debug, Clone)]
 pub struct ScopeNode {
     pub parent: Scope,
     pub nested: Vec<Scope>,
+}
 impl ScopeNode {
     pub(crate) fn new_invalid() -> Self {
         ScopeNode{
             parent: Scope::Definition(DefinitionId::new_invalid()),
             nested: Vec::new(),
+        }
+    }
+}
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub enum VariableKind {
     Parameter,      // in parameter list of function/component
     Local,          // declared in function/component body
     Binding,        // may be bound to in a binding expression (determined in validator/linker)
+}
 #[derive(Debug, Clone)]
 pub struct Variable {
     pub this: VariableId,
     // Parsing
     pub kind: VariableKind,
     pub parser_type: ParserType,
     pub identifier: Identifier,
     // Validator/linker
     pub relative_pos_in_block: u32,
     pub unique_id_in_scope: i32, // Temporary fix until proper bytecode/asm is generated
+}
 #[derive(Debug, Clone)]
 pub enum Definition {
     Struct(StructDefinition),
     Enum(EnumDefinition),
     Union(UnionDefinition),
     Component(ComponentDefinition),
     Function(FunctionDefinition),
+}
 impl Definition {
     pub fn is_struct(&self) -> bool {
         match self {
             Definition::Struct(_) => true,
             _ => false
+        }
+    }
     pub(crate) fn as_struct(&self) -> &StructDefinition {
         match self {
             Definition::Struct(result) => result,
             _ => panic!("Unable to cast 'Definition' to 'StructDefinition'"),
+        }
+    }
     pub(crate) fn as_struct_mut(&mut self) -> &mut StructDefinition {
         match self {
             Definition::Struct(result) => result,
             _ => panic!("Unable to cast 'Definition' to 'StructDefinition'"),
+        }
+    }
     pub fn is_enum(&self) -> bool {
         match self {
             Definition::Enum(_) => true,
             _ => false,
+        }
+    }
     pub(crate) fn as_enum(&self) -> &EnumDefinition {
         match self {
             Definition::Enum(result) => result,
             _ => panic!("Unable to cast 'Definition' to 'EnumDefinition'"),
+        }
+    }
     pub(crate) fn as_enum_mut(&mut self) -> &mut EnumDefinition {
         match self {
             Definition::Enum(result) => result,
             _ => panic!("Unable to cast 'Definition' to 'EnumDefinition'"),
+        }
+    }
     pub fn is_union(&self) -> bool {
         match self {
             Definition::Union(_) => true,
             _ => false,
+        }
+    }
     pub(crate) fn as_union(&self) -> &UnionDefinition {
         match self {
             Definition::Union(result) => result,
             _ => panic!("Unable to cast 'Definition' to 'UnionDefinition'"),
+        }
+    }
     pub(crate) fn as_union_mut(&mut self) -> &mut UnionDefinition {
         match self {
             Definition::Union(result) => result,
             _ => panic!("Unable to cast 'Definition' to 'UnionDefinition'"),
+        }
+    }
     pub fn is_component(&self) -> bool {
         match self {
             Definition::Component(_) => true,
             _ => false,
+        }
+    }
     pub(crate) fn as_component(&self) -> &ComponentDefinition {
         match self {
             Definition::Component(result) => result,
             _ => panic!("Unable to cast `Definition` to `Component`"),
+        }
+    }
     pub(crate) fn as_component_mut(&mut self) -> &mut ComponentDefinition {
         match self {
             Definition::Component(result) => result,
             _ => panic!("Unable to cast `Definition` to `Component`"),
+        }
+    }
     pub fn is_function(&self) -> bool {
         match self {
             Definition::Function(_) => true,
             _ => false,
+        }
+    }
     pub(crate) fn as_function(&self) -> &FunctionDefinition {
         match self {
             Definition::Function(result) => result,
             _ => panic!("Unable to cast `Definition` to `Function`"),
+        }
+    }
     pub(crate) fn as_function_mut(&mut self) -> &mut FunctionDefinition {
         match self {
             Definition::Function(result) => result,
             _ => panic!("Unable to cast `Definition` to `Function`"),
+        }
+    }
     pub fn parameters(&self) -> &Vec<VariableId> {
         match self {
             Definition::Component(def) => &def.parameters,
             Definition::Function(def) => &def.parameters,
             _ => panic!("Called parameters() on {:?}", self)
+        }
+    }
     pub fn defined_in(&self) -> RootId {
         match self {
             Definition::Struct(def) => def.defined_in,
             Definition::Enum(def) => def.defined_in,
             Definition::Union(def) => def.defined_in,
             Definition::Component(def) => def.defined_in,
             Definition::Function(def) => def.defined_in,
+        }
+    }
     pub fn identifier(&self) -> &Identifier {
         match self {
             Definition::Struct(def) => &def.identifier,
             Definition::Enum(def) => &def.identifier,
             Definition::Union(def) => &def.identifier,
             Definition::Component(def) => &def.identifier,
             Definition::Function(def) => &def.identifier,
+        }
+    }
     pub fn poly_vars(&self) -> &Vec<Identifier> {
         match self {
             Definition::Struct(def) => &def.poly_vars,
             Definition::Enum(def) => &def.poly_vars,
             Definition::Union(def) => &def.poly_vars,
             Definition::Component(def) => &def.poly_vars,
             Definition::Function(def) => &def.poly_vars,
+        }
+    }
+}
 #[derive(Debug, Clone)]
 pub struct StructFieldDefinition {
     pub span: InputSpan,
     pub field: Identifier,
     pub parser_type: ParserType,
+}
 #[derive(Debug, Clone)]
 pub struct StructDefinition {
     pub this: StructDefinitionId,
     pub defined_in: RootId,
     // Symbol scanning
     pub span: InputSpan,
     pub identifier: Identifier,
     pub poly_vars: Vec<Identifier>,
     // Parsing
     pub fields: Vec<StructFieldDefinition>
+}
 impl StructDefinition {
     pub(crate) fn new_empty(
         this: StructDefinitionId, defined_in: RootId, span: InputSpan,
         identifier: Identifier, poly_vars: Vec<Identifier>
     ) -> Self {
         Self{ this, defined_in, span, identifier, poly_vars, fields: Vec::new() }
+    }
+}
 #[derive(Debug, Clone, Copy)]
 pub enum EnumVariantValue {
     None,
     Integer(i64),
+}
 #[derive(Debug, Clone)]
 pub struct EnumVariantDefinition {
     pub identifier: Identifier,
     pub value: EnumVariantValue,
+}
 #[derive(Debug, Clone)]
 pub struct EnumDefinition {
     pub this: EnumDefinitionId,
     pub defined_in: RootId,
     // Symbol scanning
     pub span: InputSpan,
     pub identifier: Identifier,
     pub poly_vars: Vec<Identifier>,
     // Parsing
     pub variants: Vec<EnumVariantDefinition>,
+}
 impl EnumDefinition {
     pub(crate) fn new_empty(
         this: EnumDefinitionId, defined_in: RootId, span: InputSpan,
         identifier: Identifier, poly_vars: Vec<Identifier>
     ) -> Self {
         Self{ this, defined_in, span, identifier, poly_vars, variants: Vec::new() }
+    }
+}
 #[derive(Debug, Clone)]
 pub struct UnionVariantDefinition {
     pub span: InputSpan,
     pub identifier: Identifier,
     pub value: Vec<ParserType>, // if empty, then union variant does not contain any embedded types
+}
 #[derive(Debug, Clone)]
 pub struct UnionDefinition {
     pub this: UnionDefinitionId,
     pub defined_in: RootId,
     // Phase 1: symbol scanning
     pub span: InputSpan,
     pub identifier: Identifier,
     pub poly_vars: Vec<Identifier>,
     // Phase 2: parsing
     pub variants: Vec<UnionVariantDefinition>,
+}
 impl UnionDefinition {
     pub(crate) fn new_empty(
         this: UnionDefinitionId, defined_in: RootId, span: InputSpan,
         identifier: Identifier, poly_vars: Vec<Identifier>
     ) -> Self {
         Self{ this, defined_in, span, identifier, poly_vars, variants: Vec::new() }
+    }
+}
 #[derive(Debug, Clone, Copy)]
 pub enum ComponentVariant {
     Primitive,
     Composite,
+}
 #[derive(Debug, Clone)]
 pub struct ComponentDefinition {
     pub this: ComponentDefinitionId,
     pub defined_in: RootId,
     // Symbol scanning
     pub span: InputSpan,
     pub variant: ComponentVariant,
     pub identifier: Identifier,
     pub poly_vars: Vec<Identifier>,
     // Parsing
     pub parameters: Vec<VariableId>,
     pub body: BlockStatementId,
     // Validation/linking
     pub num_expressions_in_body: i32,
+}
 impl ComponentDefinition {
     // Used for preallocation during symbol scanning
     pub(crate) fn new_empty(
         this: ComponentDefinitionId, defined_in: RootId, span: InputSpan,
         variant: ComponentVariant, identifier: Identifier, poly_vars: Vec<Identifier>
     ) -> Self {
         Self{
             this, defined_in, span, variant, identifier, poly_vars,
             parameters: Vec::new(),
             body: BlockStatementId::new_invalid(),
             num_expressions_in_body: -1,
+        }
+    }
+}
 // Note that we will have function definitions for builtin functions as well. In
 // that case the span, the identifier span and the body are all invalid.
 #[derive(Debug, Clone)]
 pub struct FunctionDefinition {
     pub this: FunctionDefinitionId,
     pub defined_in: RootId,
     // Symbol scanning
     pub builtin: bool,
     pub span: InputSpan,
     pub identifier: Identifier,
     pub poly_vars: Vec<Identifier>,
     // Parser
     pub return_types: Vec<ParserType>,
     pub parameters: Vec<VariableId>,
     pub body: BlockStatementId,
     // Validation/linking
     pub num_expressions_in_body: i32,
+}
 impl FunctionDefinition {
     pub(crate) fn new_empty(
         this: FunctionDefinitionId, defined_in: RootId, span: InputSpan,
         identifier: Identifier, poly_vars: Vec<Identifier>
     ) -> Self {
         Self {
             this, defined_in,
             builtin: false,
             span, identifier, poly_vars,
             return_types: Vec::new(),
             parameters: Vec::new(),
             body: BlockStatementId::new_invalid(),
             num_expressions_in_body: -1,
+        }
+    }
+}
 #[derive(Debug, Clone)]
 pub enum Statement {
     Block(BlockStatement),
     EndBlock(EndBlockStatement),
     Local(LocalStatement),
     Labeled(LabeledStatement),
     If(IfStatement),
     EndIf(EndIfStatement),
     While(WhileStatement),
     EndWhile(EndWhileStatement),
     Break(BreakStatement),
     Continue(ContinueStatement),
     Synchronous(SynchronousStatement),
     EndSynchronous(EndSynchronousStatement),
     Fork(ForkStatement),
     EndFork(EndForkStatement),
     Return(ReturnStatement),
     Goto(GotoStatement),
     New(NewStatement),
     Expression(ExpressionStatement),
+}
 impl Statement {
     pub fn as_block(&self) -> &BlockStatement {
         match self {
             Statement::Block(result) => result,
             _ => panic!("Unable to cast `Statement` to `BlockStatement`"),
+        }
+    }
     pub fn as_local(&self) -> &LocalStatement {
         match self {
             Statement::Local(result) => result,
             _ => panic!("Unable to cast `Statement` to `LocalStatement`"),
+        }
+    }
     pub fn as_memory(&self) -> &MemoryStatement {
         self.as_local().as_memory()
+    }
     pub fn as_channel(&self) -> &ChannelStatement {
         self.as_local().as_channel()
+    }
     pub fn as_new(&self) -> &NewStatement {
         match self {
             Statement::New(result) => result,
             _ => panic!("Unable to cast `Statement` to `NewStatement`"),
+        }
+    }
     pub fn span(&self) -> InputSpan {
         match self {
             Statement::Block(v) => v.span,
             Statement::Local(v) => v.span(),
             Statement::Labeled(v) => v.label.span,
             Statement::If(v) => v.span,
             Statement::While(v) => v.span,
             Statement::Break(v) => v.span,
             Statement::Continue(v) => v.span,
             Statement::Synchronous(v) => v.span,
             Statement::Fork(v) => v.span,
             Statement::Return(v) => v.span,
             Statement::Goto(v) => v.span,
             Statement::New(v) => v.span,
             Statement::Expression(v) => v.span,
             Statement::EndBlock(_) | Statement::EndIf(_) | Statement::EndWhile(_) | Statement::EndSynchronous(_) | Statement::EndFork(_) => unreachable!(),
+        }
+    }
     pub fn link_next(&mut self, next: StatementId) {
         match self {
             Statement::Block(stmt) => stmt.next = next,
             Statement::EndBlock(stmt) => stmt.next = next,
             Statement::Local(stmt) => match stmt {
                 LocalStatement::Channel(stmt) => stmt.next = next,
                 LocalStatement::Memory(stmt) => stmt.next = next,
             },
             Statement::EndIf(stmt) => stmt.next = next,
             Statement::EndWhile(stmt) => stmt.next = next,
             Statement::EndSynchronous(stmt) => stmt.next = next,
             Statement::EndFork(stmt) => stmt.next = next,
             Statement::New(stmt) => stmt.next = next,
             Statement::Expression(stmt) => stmt.next = next,
             Statement::Return(_)
             | Statement::Break(_)
             | Statement::Continue(_)
             | Statement::Synchronous(_)
             | Statement::Fork(_)
             | Statement::Goto(_)
             | Statement::While(_)
             | Statement::Labeled(_)
             | Statement::If(_) => unreachable!(),
+        }
+    }
+}
 #[derive(Debug, Clone)]
 pub struct BlockStatement {
     pub this: BlockStatementId,
     // Phase 1: parser
     pub is_implicit: bool,
     pub span: InputSpan, // of the complete block
     pub statements: Vec<StatementId>,
     pub end_block: EndBlockStatementId,
     // Phase 2: linker
     pub scope_node: ScopeNode,
     pub first_unique_id_in_scope: i32, // Temporary fix until proper bytecode/asm is generated
     pub next_unique_id_in_scope: i32, // Temporary fix until proper bytecode/asm is generated
     pub relative_pos_in_parent: u32,
     pub locals: Vec<VariableId>,
     pub labels: Vec<LabeledStatementId>,
     pub next: StatementId,
+}
 #[derive(Debug, Clone)]
 pub struct EndBlockStatement {
     pub this: EndBlockStatementId,
     // Parser
     pub start_block: BlockStatementId,
     // Validation/Linking
     pub next: StatementId,
+}
 #[derive(Debug, Clone)]
 pub enum LocalStatement {
     Memory(MemoryStatement),
     Channel(ChannelStatement),
+}
 impl LocalStatement {
     pub fn this(&self) -> LocalStatementId {
         match self {
             LocalStatement::Memory(stmt) => stmt.this.upcast(),
             LocalStatement::Channel(stmt) => stmt.this.upcast(),
+        }
+    }
     pub fn as_memory(&self) -> &MemoryStatement {
         match self {
             LocalStatement::Memory(result) => result,
             _ => panic!("Unable to cast `LocalStatement` to `MemoryStatement`"),
+        }
+    }
     pub fn as_channel(&self) -> &ChannelStatement {
         match self {
             LocalStatement::Channel(result) => result,
             _ => panic!("Unable to cast `LocalStatement` to `ChannelStatement`"),
+        }
+    }
     pub fn span(&self) -> InputSpan {
         match self {
             LocalStatement::Channel(v) => v.span,
             LocalStatement::Memory(v) => v.span,
+        }
+    }
+}
 #[derive(Debug, Clone)]
 pub struct MemoryStatement {
     pub this: MemoryStatementId,
     // Phase 1: parser
     pub span: InputSpan,
     pub variable: VariableId,
     // Phase 2: linker
     pub next: StatementId,
+}
 /// ChannelStatement is the declaration of an input and output port associated
 /// with the same channel. Note that the polarity of the ports are from the
 /// point of view of the component. So an output port is something that a
 /// component uses to send data over (i.e. it is the "input end" of the
 /// channel), and vice versa.
 #[derive(Debug, Clone)]
 pub struct ChannelStatement {
     pub this: ChannelStatementId,
     // Phase 1: parser
     pub span: InputSpan, // of the "channel" keyword
     pub from: VariableId, // output
     pub to: VariableId,   // input
     // Phase 2: linker
     pub relative_pos_in_block: u32,
     pub next: StatementId,
+}
 #[derive(Debug, Clone)]
 pub struct LabeledStatement {
     pub this: LabeledStatementId,
     // Phase 1: parser
     pub label: Identifier,
     pub body: StatementId,
     // Phase 2: linker
     pub relative_pos_in_block: u32,
     pub in_sync: SynchronousStatementId, // may be invalid
+}
 #[derive(Debug, Clone)]
 pub struct IfStatement {
     pub this: IfStatementId,
     // Phase 1: parser
     pub span: InputSpan, // of the "if" keyword
     pub test: ExpressionId,
     pub true_body: BlockStatementId,
     pub false_body: Option<BlockStatementId>,
     pub end_if: EndIfStatementId,
+}
 #[derive(Debug, Clone)]
 pub struct EndIfStatement {
     pub this: EndIfStatementId,
     pub start_if: IfStatementId,
     pub next: StatementId,
+}
 #[derive(Debug, Clone)]
 pub struct WhileStatement {
     pub this: WhileStatementId,
     // Phase 1: parser
     pub span: InputSpan, // of the "while" keyword
     pub test: ExpressionId,
     pub body: BlockStatementId,
     pub end_while: EndWhileStatementId,
     pub in_sync: SynchronousStatementId, // may be invalid
+}
 #[derive(Debug, Clone)]
 pub struct EndWhileStatement {
     pub this: EndWhileStatementId,
     pub start_while: WhileStatementId,
     // Phase 2: linker
     pub next: StatementId,
+}
 #[derive(Debug, Clone)]
 pub struct BreakStatement {
     pub this: BreakStatementId,
     // Phase 1: parser
     pub span: InputSpan, // of the "break" keyword
     pub label: Option<Identifier>,
     // Phase 2: linker
     pub target: Option<EndWhileStatementId>,
+}
 #[derive(Debug, Clone)]
 pub struct ContinueStatement {
     pub this: ContinueStatementId,
     // Phase 1: parser
     pub span: InputSpan, // of the "continue" keyword
     pub label: Option<Identifier>,
     // Phase 2: linker
     pub target: Option<WhileStatementId>,
+}
 #[derive(Debug, Clone)]
 pub struct SynchronousStatement {
     pub this: SynchronousStatementId,
     // Phase 1: parser
     pub span: InputSpan, // of the "sync" keyword
     pub body: BlockStatementId,
     pub end_sync: EndSynchronousStatementId,
+}
 #[derive(Debug, Clone)]
 pub struct EndSynchronousStatement {
     pub this: EndSynchronousStatementId,
     pub start_sync: SynchronousStatementId,
     // Phase 2: linker
     pub next: StatementId,
+}
 #[derive(Debug, Clone)]
 pub struct ForkStatement {
     pub this: ForkStatementId,
     // Phase 1: parser
     pub span: InputSpan, // of the "fork" keyword
     pub left_body: BlockStatementId,
     pub right_body: Option<BlockStatementId>,
     pub end_fork: EndForkStatementId,
+}
 #[derive(Debug, Clone)]
 pub struct EndForkStatement {
     pub this: EndForkStatementId,
     pub start_fork: ForkStatementId,
     pub next: StatementId,
+}
 #[derive(Debug, Clone)]
 pub struct ReturnStatement {
     pub this: ReturnStatementId,
     // Phase 1: parser
     pub span: InputSpan, // of the "return" keyword
     pub expressions: Vec<ExpressionId>,
+}
 #[derive(Debug, Clone)]
 pub struct GotoStatement {
     pub this: GotoStatementId,
     // Phase 1: parser
     pub span: InputSpan, // of the "goto" keyword
     pub label: Identifier,
     // Phase 2: linker
     pub target: Option<LabeledStatementId>,
+}
 #[derive(Debug, Clone)]
 pub struct NewStatement {
     pub this: NewStatementId,
     // Phase 1: parser
     pub span: InputSpan, // of the "new" keyword
     pub expression: CallExpressionId,
     // Phase 2: linker
     pub next: StatementId,
+}
 #[derive(Debug, Clone)]
 pub struct ExpressionStatement {
     pub this: ExpressionStatementId,
     // Phase 1: parser
     pub span: InputSpan,
     pub expression: ExpressionId,
     // Phase 2: linker
     pub next: StatementId,
+}
 #[derive(Debug, PartialEq, Eq, Clone, Copy)]
 pub enum ExpressionParent {
     None, // only set during initial parsing
     If(IfStatementId),
     While(WhileStatementId),
     Return(ReturnStatementId),
     New(NewStatementId),
     ExpressionStmt(ExpressionStatementId),
     Expression(ExpressionId, u32) // index within expression (e.g LHS or RHS of expression)
+}
 impl ExpressionParent {
     pub fn is_new(&self) -> bool {
         match self {
             ExpressionParent::New(_) => true,
             _ => false,
+        }
+    }
     pub fn as_expression(&self) -> ExpressionId {
         match self {
             ExpressionParent::Expression(id, _) => *id,
             _ => panic!("called as_expression() on {:?}", self),
+        }
+    }
+}
 #[derive(Debug, Clone)]
 pub enum Expression {
     Assignment(AssignmentExpression),
     Binding(BindingExpression),
     Conditional(ConditionalExpression),
     Binary(BinaryExpression),
     Unary(UnaryExpression),
     Indexing(IndexingExpression),
     Slicing(SlicingExpression),
     Select(SelectExpression),
     Literal(LiteralExpression),
     Cast(CastExpression),
     Call(CallExpression),
     Variable(VariableExpression),
+}
 impl Expression {
     pub fn as_variable(&self) -> &VariableExpression {
         match self {
             Expression::Variable(result) => result,
             _ => panic!("Unable to cast `Expression` to `VariableExpression`"),
+        }
+    }
     /// Returns operator span, function name, a binding's "let" span, etc. An
     /// indicator for the kind of expression that is being applied.
     pub fn operation_span(&self) -> InputSpan {
         match self {
             Expression::Assignment(expr) => expr.operator_span,
             Expression::Binding(expr) => expr.operator_span,
             Expression::Conditional(expr) => expr.operator_span,
             Expression::Binary(expr) => expr.operator_span,
             Expression::Unary(expr) => expr.operator_span,
             Expression::Indexing(expr) => expr.operator_span,
             Expression::Slicing(expr) => expr.slicing_span,
             Expression::Select(expr) => expr.operator_span,
             Expression::Literal(expr) => expr.span,
             Expression::Cast(expr) => expr.cast_span,
             Expression::Call(expr) => expr.func_span,
             Expression::Variable(expr) => expr.identifier.span,
+        }
+    }
     /// Returns the span covering the entire expression (i.e. including the
     /// spans of the arguments as well).
     pub fn full_span(&self) -> InputSpan {
         match self {
             Expression::Assignment(expr) => expr.full_span,
             Expression::Binding(expr) => expr.full_span,
             Expression::Conditional(expr) => expr.full_span,
             Expression::Binary(expr) => expr.full_span,
             Expression::Unary(expr) => expr.full_span,
             Expression::Indexing(expr) => expr.full_span,
             Expression::Slicing(expr) => expr.full_span,
             Expression::Select(expr) => expr.full_span,
             Expression::Literal(expr) => expr.span,
             Expression::Cast(expr) => expr.full_span,
             Expression::Call(expr) => expr.full_span,
             Expression::Variable(expr) => expr.identifier.span,
+        }
+    }
     pub fn parent(&self) -> &ExpressionParent {
         match self {
             Expression::Assignment(expr) => &expr.parent,
             Expression::Binding(expr) => &expr.parent,
             Expression::Conditional(expr) => &expr.parent,
             Expression::Binary(expr) => &expr.parent,
             Expression::Unary(expr) => &expr.parent,
             Expression::Indexing(expr) => &expr.parent,
             Expression::Slicing(expr) => &expr.parent,
             Expression::Select(expr) => &expr.parent,
             Expression::Literal(expr) => &expr.parent,
             Expression::Cast(expr) => &expr.parent,
             Expression::Call(expr) => &expr.parent,
             Expression::Variable(expr) => &expr.parent,
+        }
+    }
     pub fn parent_expr_id(&self) -> Option<ExpressionId> {
         if let ExpressionParent::Expression(id, _) = self.parent() {
             Some(*id)
         } else {
             None
+        }
+    }
     pub fn get_unique_id_in_definition(&self) -> i32 {
         match self {
             Expression::Assignment(expr) => expr.unique_id_in_definition,
             Expression::Binding(expr) => expr.unique_id_in_definition,
             Expression::Conditional(expr) => expr.unique_id_in_definition,
             Expression::Binary(expr) => expr.unique_id_in_definition,
             Expression::Unary(expr) => expr.unique_id_in_definition,
             Expression::Indexing(expr) => expr.unique_id_in_definition,
             Expression::Slicing(expr) => expr.unique_id_in_definition,
             Expression::Select(expr) => expr.unique_id_in_definition,
             Expression::Literal(expr) => expr.unique_id_in_definition,
             Expression::Cast(expr) => expr.unique_id_in_definition,
             Expression::Call(expr) => expr.unique_id_in_definition,
             Expression::Variable(expr) => expr.unique_id_in_definition,
+        }
+    }
+}
 #[derive(Debug, Clone, Copy)]
 pub enum AssignmentOperator {
     Set,
     Concatenated,
     Multiplied,
     Divided,
     Remained,
     Added,
     Subtracted,
     ShiftedLeft,
     ShiftedRight,
     BitwiseAnded,
     BitwiseXored,
     BitwiseOred,
+}
 #[derive(Debug, Clone)]
 pub struct AssignmentExpression {
     pub this: AssignmentExpressionId,
     // Parsing
     pub operator_span: InputSpan,
     pub full_span: InputSpan,
     pub left: ExpressionId,
     pub operation: AssignmentOperator,
     pub right: ExpressionId,
     // Validator/Linker
     pub parent: ExpressionParent,
     pub unique_id_in_definition: i32,
+}
 #[derive(Debug, Clone)]
 pub struct BindingExpression {
     pub this: BindingExpressionId,
     // Parsing
     pub operator_span: InputSpan,
     pub full_span: InputSpan,
     pub bound_to: ExpressionId,
     pub bound_from: ExpressionId,
     // Validator/Linker
     pub parent: ExpressionParent,
     pub unique_id_in_definition: i32,
+}
 #[derive(Debug, Clone)]
 pub struct ConditionalExpression {
     pub this: ConditionalExpressionId,
     // Parsing
     pub operator_span: InputSpan,
     pub full_span: InputSpan,
     pub test: ExpressionId,
     pub true_expression: ExpressionId,
     pub false_expression: ExpressionId,
     // Validator/Linking
     pub parent: ExpressionParent,
     pub unique_id_in_definition: i32,
+}
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub enum BinaryOperator {
     Concatenate,
     LogicalOr,
     LogicalAnd,
     BitwiseOr,
     BitwiseXor,
     BitwiseAnd,
     Equality,
     Inequality,
     LessThan,
     GreaterThan,
     LessThanEqual,
     GreaterThanEqual,
     ShiftLeft,
     ShiftRight,
     Add,
     Subtract,
     Multiply,
     Divide,
     Remainder,
+}
 #[derive(Debug, Clone)]
 pub struct BinaryExpression {
     pub this: BinaryExpressionId,
     // Parsing
     pub operator_span: InputSpan,
     pub full_span: InputSpan,
     pub left: ExpressionId,
     pub operation: BinaryOperator,
     pub right: ExpressionId,
     // Validator/Linker
     pub parent: ExpressionParent,
     pub unique_id_in_definition: i32,
+}
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub enum UnaryOperator {
     Positive,
     Negative,
     BitwiseNot,
     LogicalNot,
+}
 #[derive(Debug, Clone)]
 pub struct UnaryExpression {
     pub this: UnaryExpressionId,
     // Parsing
     pub operator_span: InputSpan,
     pub full_span: InputSpan,
     pub operation: UnaryOperator,
     pub expression: ExpressionId,
     // Validator/Linker
     pub parent: ExpressionParent,
     pub unique_id_in_definition: i32,
+}
 #[derive(Debug, Clone)]
 pub struct IndexingExpression {
     pub this: IndexingExpressionId,
     // Parsing
     pub operator_span: InputSpan,
     pub full_span: InputSpan,
     pub subject: ExpressionId,
     pub index: ExpressionId,
     // Validator/Linker
     pub parent: ExpressionParent,
     pub unique_id_in_definition: i32,
+}
 #[derive(Debug, Clone)]
 pub struct SlicingExpression {
     pub this: SlicingExpressionId,
     // Parsing
     pub slicing_span: InputSpan, // from '[' to ']'
     pub full_span: InputSpan, // includes subject
     pub subject: ExpressionId,
     pub from_index: ExpressionId,
     pub to_index: ExpressionId,
     // Validator/Linker
     pub parent: ExpressionParent,
     pub unique_id_in_definition: i32,
+}
 #[derive(Debug, Clone)]
 pub struct SelectExpression {
     pub this: SelectExpressionId,
     // Parsing
     pub operator_span: InputSpan, // of the '.'
     pub full_span: InputSpan, // includes subject and field
     pub subject: ExpressionId,
     pub field_name: Identifier,
     // Validator/Linker
     pub parent: ExpressionParent,
     pub unique_id_in_definition: i32,
+}
 #[derive(Debug, Clone)]
 pub struct CastExpression {
     pub this: CastExpressionId,
     // Parsing
     pub cast_span: InputSpan, // of the "cast" keyword,
     pub full_span: InputSpan, // includes the cast subject
     pub to_type: ParserType,
     pub subject: ExpressionId,
     // Validator/linker
     pub parent: ExpressionParent,
     pub unique_id_in_definition: i32,
+}
 #[derive(Debug, Clone)]
 pub struct CallExpression {
     pub this: CallExpressionId,
     // Parsing
     pub func_span: InputSpan, // of the function name
     pub full_span: InputSpan, // includes the arguments and parentheses
     pub parser_type: ParserType, // of the function call, not the return type
     pub method: Method,
     pub arguments: Vec<ExpressionId>,
     pub definition: DefinitionId,
     // Validator/Linker
     pub parent: ExpressionParent,
     pub unique_id_in_definition: i32,
+}
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub enum Method {
     // Builtin
     Get,
     Put,
     Fires,
     Create,
     Length,
     Assert,
     Print,
     UserFunction,
     UserComponent,
+}
 #[derive(Debug, Clone)]
 pub struct MethodSymbolic {
     pub(crate) parser_type: ParserType,
     pub(crate) definition: DefinitionId
+}
 #[derive(Debug, Clone)]
 pub struct LiteralExpression {
     pub this: LiteralExpressionId,
     // Parsing
     pub span: InputSpan,
     pub value: Literal,
     // Validator/Linker
     pub parent: ExpressionParent,
     pub unique_id_in_definition: i32,
+}
 #[derive(Debug, Clone)]
 pub enum Literal {
     Null, // message
     True,
     False,
     Character(char),
     String(StringRef<'static>),
     Integer(LiteralInteger),
     Struct(LiteralStruct),
     Enum(LiteralEnum),
     Union(LiteralUnion),
     Array(Vec<ExpressionId>),
+}
 impl Literal {
     pub(crate) fn as_struct(&self) -> &LiteralStruct {
         if let Literal::Struct(literal) = self{
             literal
         } else {
             unreachable!("Attempted to obtain {:?} as Literal::Struct", self)
+        }
+    }
     pub(crate) fn as_enum(&self) -> &LiteralEnum {
         if let Literal::Enum(literal) = self {
             literal
         } else {
             unreachable!("Attempted to obtain {:?} as Literal::Enum", self)
+        }
+    }
     pub(crate) fn as_union(&self) -> &LiteralUnion {
         if let Literal::Union(literal) = self {
             literal
         } else {
             unreachable!("Attempted to obtain {:?} as Literal::Union", self)
+        }
+    }
+}
 #[derive(Debug, Clone)]
 pub struct LiteralInteger {
     pub(crate) unsigned_value: u64,
     pub(crate) negated: bool, // for constant expression evaluation, TODO: @Int
+}
 #[derive(Debug, Clone)]
 pub struct LiteralStructField {
     // Phase 1: parser
     pub(crate) identifier: Identifier,
     pub(crate) value: ExpressionId,
     // Phase 2: linker
     pub(crate) field_idx: usize, // in struct definition
+}
 #[derive(Debug, Clone)]
 pub struct LiteralStruct {
     // Phase 1: parser
     pub(crate) parser_type: ParserType,
     pub(crate) fields: Vec<LiteralStructField>,
     pub(crate) definition: DefinitionId,
+}
 #[derive(Debug, Clone)]
 pub struct LiteralEnum {
     // Phase 1: parser
     pub(crate) parser_type: ParserType,
     pub(crate) variant: Identifier,
     pub(crate) definition: DefinitionId,
     // Phase 2: linker
     pub(crate) variant_idx: usize, // as present in the type table
+}
 #[derive(Debug, Clone)]
 pub struct LiteralUnion {
     // Phase 1: parser
     pub(crate) parser_type: ParserType,
     pub(crate) variant: Identifier,
     pub(crate) values: Vec<ExpressionId>,
     pub(crate) definition: DefinitionId,
     // Phase 2: linker
     pub(crate) variant_idx: usize, // as present in type table
+}
 #[derive(Debug, Clone)]
 pub struct VariableExpression {
     pub this: VariableExpressionId,
     // Parsing
     pub identifier: Identifier,
     // Validator/Linker
     pub declaration: Option<VariableId>,
     pub used_as_binding_target: bool,
     pub parent: ExpressionParent,
     pub unique_id_in_definition: i32,
+}
@@ \ No newline at end of file @@

src/protocol/eval/executor.rs

➞

Show inline comments

 use std::collections::VecDeque;
 use super::value::*;
 use super::store::*;
 use super::error::*;
 use crate::protocol::*;
 use crate::protocol::ast::*;
 use crate::protocol::type_table::*;
 macro_rules! debug_enabled { () => { false }; }
 macro_rules! debug_log {
     ($format:literal) => {
         enabled_debug_print!(false, "exec", $format);
     };
     ($format:literal, $($args:expr),*) => {
         enabled_debug_print!(false, "exec", $format, $($args),*);
     };
+}
 #[derive(Debug, Clone)]
 pub(crate) enum ExprInstruction {
     EvalExpr(ExpressionId),
     PushValToFront,
+}
 #[derive(Debug, Clone)]
 pub(crate) struct Frame {
     pub(crate) definition: DefinitionId,
     pub(crate) monomorph_idx: i32,
     pub(crate) position: StatementId,
     pub(crate) expr_stack: VecDeque<ExprInstruction>, // hack for expression evaluation, evaluated by popping from back
     pub(crate) expr_values: VecDeque<Value>, // hack for expression results, evaluated by popping from front/back
     pub(crate) max_stack_size: u32,
+}
 impl Frame {
     /// Creates a new execution frame. Does not modify the stack in any way.
     pub fn new(heap: &Heap, definition_id: DefinitionId, monomorph_idx: i32) -> Self {
         let definition = &heap[definition_id];
         let first_statement = match definition {
             Definition::Component(definition) => definition.body,
             Definition::Function(definition) => definition.body,
             _ => unreachable!("initializing frame with {:?} instead of a function/component", definition),
         };
         // Another not-so-pretty thing that has to be replaced somewhere in the
         // future...
         fn determine_max_stack_size(heap: &Heap, block_id: BlockStatementId, max_size: &mut u32) {
             let block_stmt = &heap[block_id];
             debug_assert!(block_stmt.next_unique_id_in_scope >= 0);
             // Check current block
             let cur_size = block_stmt.next_unique_id_in_scope as u32;
             if cur_size > *max_size { *max_size = cur_size; }
             // And child blocks
             for child_scope in &block_stmt.scope_node.nested {
                 determine_max_stack_size(heap, child_scope.to_block(), max_size);
+            }
+        }
         let mut max_stack_size = 0;
         determine_max_stack_size(heap, first_statement, &mut max_stack_size);
         Frame{
             definition: definition_id,
             monomorph_idx,
             position: first_statement.upcast(),
             expr_stack: VecDeque::with_capacity(128),
             expr_values: VecDeque::with_capacity(128),
             max_stack_size,
+        }
+    }
     /// Prepares a single expression for execution. This involves walking the
     /// expression tree and putting them in the `expr_stack` such that
     /// continuously popping from its back will evaluate the expression. The
     /// results of each expression will be stored by pushing onto `expr_values`.
     pub fn prepare_single_expression(&mut self, heap: &Heap, expr_id: ExpressionId) {
         debug_assert!(self.expr_stack.is_empty());
         self.expr_values.clear(); // May not be empty if last expression result(s) were discarded
         self.serialize_expression(heap, expr_id);
+    }
     /// Prepares multiple expressions for execution (i.e. evaluating all
     /// function arguments or all elements of an array/union literal). Per
     /// expression this works the same as `prepare_single_expression`. However
     /// after each expression is evaluated we insert a `PushValToFront`
     /// instruction
     pub fn prepare_multiple_expressions(&mut self, heap: &Heap, expr_ids: &[ExpressionId]) {
         debug_assert!(self.expr_stack.is_empty());
         self.expr_values.clear();
         for expr_id in expr_ids {
             self.expr_stack.push_back(ExprInstruction::PushValToFront);
             self.serialize_expression(heap, *expr_id);
+        }
+    }
     /// Performs depth-first serialization of expression tree. Let's not care
     /// about performance for a temporary runtime implementation
     fn serialize_expression(&mut self, heap: &Heap, id: ExpressionId) {
         self.expr_stack.push_back(ExprInstruction::EvalExpr(id));
         match &heap[id] {
             Expression::Assignment(expr) => {
                 self.serialize_expression(heap, expr.left);
                 self.serialize_expression(heap, expr.right);
             },
             Expression::Binding(expr) => {
                 self.serialize_expression(heap, expr.bound_to);
                 self.serialize_expression(heap, expr.bound_from);
             },
             Expression::Conditional(expr) => {
                 self.serialize_expression(heap, expr.test);
             },
             Expression::Binary(expr) => {
                 self.serialize_expression(heap, expr.left);
                 self.serialize_expression(heap, expr.right);
             },
             Expression::Unary(expr) => {
                 self.serialize_expression(heap, expr.expression);
             },
             Expression::Indexing(expr) => {
                 self.serialize_expression(heap, expr.index);
                 self.serialize_expression(heap, expr.subject);
             },
             Expression::Slicing(expr) => {
                 self.serialize_expression(heap, expr.from_index);
                 self.serialize_expression(heap, expr.to_index);
                 self.serialize_expression(heap, expr.subject);
             },
             Expression::Select(expr) => {
                 self.serialize_expression(heap, expr.subject);
             },
             Expression::Literal(expr) => {
                 // Here we only care about literals that have subexpressions
                 match &expr.value {
                     Literal::Null | Literal::True | Literal::False |
                     Literal::Character(_) | Literal::String(_) |
                     Literal::Integer(_) | Literal::Enum(_) => {
                         // No subexpressions
                     },
                     Literal::Struct(literal) => {
                         // Note: fields expressions are evaluated in programmer-
                         // specified order. But struct construction expects them
                         // in type-defined order. I might want to come back to
                         // this.
                         let mut _num_pushed = 0;
                         for want_field_idx in 0..literal.fields.len() {
                             for field in &literal.fields {
                                 if field.field_idx == want_field_idx {
                                     _num_pushed += 1;
                                     self.expr_stack.push_back(ExprInstruction::PushValToFront);
                                     self.serialize_expression(heap, field.value);
+                                }
+                            }
+                        }
                         debug_assert_eq!(_num_pushed, literal.fields.len())
                     },
                     Literal::Union(literal) => {
                         for value_expr_id in &literal.values {
                             self.expr_stack.push_back(ExprInstruction::PushValToFront);
                             self.serialize_expression(heap, *value_expr_id);
+                        }
                     },
                     Literal::Array(value_expr_ids) => {
                         for value_expr_id in value_expr_ids {
                             self.expr_stack.push_back(ExprInstruction::PushValToFront);
                             self.serialize_expression(heap, *value_expr_id);
+                        }
+                    }
+                }
             },
             Expression::Cast(expr) => {
                 self.serialize_expression(heap, expr.subject);
+            }
             Expression::Call(expr) => {
                 for arg_expr_id in &expr.arguments {
                     self.expr_stack.push_back(ExprInstruction::PushValToFront);
                     self.serialize_expression(heap, *arg_expr_id);
+                }
             },
             Expression::Variable(_expr) => {
                 // No subexpressions
+            }
+        }
+    }
+}
 type EvalResult = Result<EvalContinuation, EvalError>;
 #[derive(Debug)]
 pub enum EvalContinuation {
     // Returned in both sync and non-sync modes
     Stepping,
     // Returned only in sync mode
     BranchInconsistent,
     SyncBlockEnd,
     NewFork,
     BlockFires(PortId),
     BlockGet(PortId),
     Put(PortId, ValueGroup),
     // Returned only in non-sync mode
     ComponentTerminated,
     SyncBlockStart,
     NewComponent(DefinitionId, i32, ValueGroup),
     NewChannel,
+}
 // Note: cloning is fine, methinks. cloning all values and the heap regions then
 // we end up with valid "pointers" to heap regions.
 #[derive(Debug, Clone)]
 pub struct Prompt {
     pub(crate) frames: Vec<Frame>,
     pub(crate) store: Store,
+}
 impl Prompt {
     pub fn new(_types: &TypeTable, heap: &Heap, def: DefinitionId, monomorph_idx: i32, args: ValueGroup) -> Self {
         let mut prompt = Self{
             frames: Vec::new(),
             store: Store::new(),
         };
         // Maybe do typechecking in the future?
         debug_assert!((monomorph_idx as usize) < _types.get_base_definition(&def).unwrap().definition.procedure_monomorphs().len());
         let new_frame = Frame::new(heap, def, monomorph_idx);
         let max_stack_size = new_frame.max_stack_size;
         prompt.frames.push(new_frame);
         args.into_store(&mut prompt.store);
         prompt.store.reserve_stack(max_stack_size);
         prompt
+    }
     /// Big 'ol function right here. Didn't want to break it up unnecessarily.
     /// It consists of, in sequence: executing any expressions that should be
     /// executed before the next statement can be evaluated, then a section that
     /// performs debug printing, and finally a section that takes the next
     /// statement and executes it. If the statement requires any expressions to
     /// be evaluated, then they will be added such that the next time `step` is
     /// called, all of these expressions are indeed evaluated.
     pub(crate) fn step(&mut self, types: &TypeTable, heap: &Heap, modules: &[Module], ctx: &mut impl RunContext) -> EvalResult {
         // Helper function to transfer multiple values from the expression value
         // array into a heap region (e.g. constructing arrays or structs).
         fn transfer_expression_values_front_into_heap(cur_frame: &mut Frame, store: &mut Store, num_values: usize) -> HeapPos {
             let heap_pos = store.alloc_heap();
             // Do the transformation first (because Rust...)
             for val_idx in 0..num_values {
                 cur_frame.expr_values[val_idx] = store.read_take_ownership(cur_frame.expr_values[val_idx].clone());
+            }
             // And now transfer to the heap region
             let values = &mut store.heap_regions[heap_pos as usize].values;
             debug_assert!(values.is_empty());
             values.reserve(num_values);
             for _ in 0..num_values {
                 values.push(cur_frame.expr_values.pop_front().unwrap());
+            }
             heap_pos
+        }
         // Helper function to make sure that an index into an aray is valid.
         fn array_inclusive_index_is_invalid(store: &Store, array_heap_pos: u32, idx: i64) -> bool {
             let array_len = store.heap_regions[array_heap_pos as usize].values.len();
             return idx < 0 || idx >= array_len as i64;
+        }
         fn array_exclusive_index_is_invalid(store: &Store, array_heap_pos: u32, idx: i64) -> bool {
             let array_len = store.heap_regions[array_heap_pos as usize].values.len();
             return idx < 0 || idx > array_len as i64;
+        }
         fn construct_array_error(prompt: &Prompt, modules: &[Module], heap: &Heap, expr_id: ExpressionId, heap_pos: u32, idx: i64) -> EvalError {
             let array_len = prompt.store.heap_regions[heap_pos as usize].values.len();
             return EvalError::new_error_at_expr(
                 prompt, modules, heap, expr_id,
                 format!("index {} is out of bounds: array length is {}", idx, array_len)
+            )
+        }
         // Checking if we're at the end of execution
         let cur_frame = self.frames.last_mut().unwrap();
         if cur_frame.position.is_invalid() {
             if heap[cur_frame.definition].is_function() {
                 todo!("End of function without return, return an evaluation error");
+            }
             return Ok(EvalContinuation::ComponentTerminated);
+        }
         debug_log!("Taking step in '{}'", heap[cur_frame.definition].identifier().value.as_str());
         // Execute all pending expressions
         while !cur_frame.expr_stack.is_empty() {
             let next = cur_frame.expr_stack.pop_back().unwrap();
             debug_log!("Expr stack: {:?}", next);
             match next {
                 ExprInstruction::PushValToFront => {
                     cur_frame.expr_values.rotate_right(1);
                 },
                 ExprInstruction::EvalExpr(expr_id) => {
                     let expr = &heap[expr_id];
                     match expr {
                         Expression::Assignment(expr) => {
                             let to = cur_frame.expr_values.pop_back().unwrap().as_ref();
                             let rhs = cur_frame.expr_values.pop_back().unwrap();
                             // Note: although not pretty, the assignment operator takes ownership
                             // of the right-hand side value when possible. So we do not drop the
                             // rhs's optionally owned heap data.
                             let rhs = self.store.read_take_ownership(rhs);
                             apply_assignment_operator(&mut self.store, to, expr.operation, rhs);
                         },
                         Expression::Binding(_expr) => {
                             let bind_to = cur_frame.expr_values.pop_back().unwrap();
                             let bind_from = cur_frame.expr_values.pop_back().unwrap();
                             let bind_to_heap_pos = bind_to.get_heap_pos();
                             let bind_from_heap_pos = bind_from.get_heap_pos();
                             let result = apply_binding_operator(&mut self.store, bind_to, bind_from);
                             self.store.drop_value(bind_to_heap_pos);
                             self.store.drop_value(bind_from_heap_pos);
                             cur_frame.expr_values.push_back(Value::Bool(result));
                         },
                         Expression::Conditional(expr) => {
                             // Evaluate testing expression, then extend the
                             // expression stack with the appropriate expression
                             let test_result = cur_frame.expr_values.pop_back().unwrap().as_bool();
                             if test_result {
                                 cur_frame.serialize_expression(heap, expr.true_expression);
                             } else {
                                 cur_frame.serialize_expression(heap, expr.false_expression);
+                            }
                         },
                         Expression::Binary(expr) => {
                             let lhs = cur_frame.expr_values.pop_back().unwrap();
                             let rhs = cur_frame.expr_values.pop_back().unwrap();
                             let result = apply_binary_operator(&mut self.store, &lhs, expr.operation, &rhs);
                             cur_frame.expr_values.push_back(result);
                             self.store.drop_value(lhs.get_heap_pos());
                             self.store.drop_value(rhs.get_heap_pos());
                         },
                         Expression::Unary(expr) => {
                             let val = cur_frame.expr_values.pop_back().unwrap();
                             let result = apply_unary_operator(&mut self.store, expr.operation, &val);
                             cur_frame.expr_values.push_back(result);
                             self.store.drop_value(val.get_heap_pos());
                         },
                         Expression::Indexing(_expr) => {
                             // Evaluate index. Never heap allocated so we do
                             // not have to drop it.
                             let index = cur_frame.expr_values.pop_back().unwrap();
                             let index = self.store.maybe_read_ref(&index);
                             debug_assert!(index.is_integer());
                             let index = if index.is_signed_integer() {
                                 index.as_signed_integer() as i64
                             } else {
                                 index.as_unsigned_integer() as i64
                             };
                             let subject = cur_frame.expr_values.pop_back().unwrap();
                             let (deallocate_heap_pos, value_to_push) = match subject {
                                 Value::Ref(value_ref) => {
                                     // Our expression stack value is a reference to something that
                                     // exists in the normal stack/heap. We don't want to deallocate
                                     // this thing. Rather we want to return a reference to it.
                                     let subject = self.store.read_ref(value_ref);
                                     let subject_heap_pos = match subject {
                                         Value::String(v) => *v,
                                         Value::Array(v) => *v,
                                         Value::Message(v) => *v,
                                         _ => unreachable!(),
                                     };
                                     if array_inclusive_index_is_invalid(&self.store, subject_heap_pos, index) {
                                         return Err(construct_array_error(self, modules, heap, expr_id, subject_heap_pos, index));
+                                    }
                                     (None, Value::Ref(ValueId::Heap(subject_heap_pos, index as u32)))
                                 },
                                 _ => {
                                     // Our value lives on the expression stack, hence we need to
                                     // clone whatever we're referring to. Then drop the subject.
                                     let subject_heap_pos = match &subject {
                                         Value::String(v) => *v,
                                         Value::Array(v) => *v,
                                         Value::Message(v) => *v,
                                         _ => unreachable!(),
                                     };
                                     if array_inclusive_index_is_invalid(&self.store, subject_heap_pos, index) {
                                         return Err(construct_array_error(self, modules, heap, expr_id, subject_heap_pos, index));
+                                    }
                                     let subject_indexed = Value::Ref(ValueId::Heap(subject_heap_pos, index as u32));
                                     (Some(subject_heap_pos), self.store.clone_value(subject_indexed))
                                 },
                             };
                             cur_frame.expr_values.push_back(value_to_push);
                             self.store.drop_value(deallocate_heap_pos);
                         },
                         Expression::Slicing(expr) => {
                             // Evaluate indices
                             let from_index = cur_frame.expr_values.pop_back().unwrap();
                             let from_index = self.store.maybe_read_ref(&from_index);
                             let to_index = cur_frame.expr_values.pop_back().unwrap();
                             let to_index = self.store.maybe_read_ref(&to_index);
                             debug_assert!(from_index.is_integer() && to_index.is_integer());
                             let from_index = if from_index.is_signed_integer() {
                                 from_index.as_signed_integer()
                             } else {
                                 from_index.as_unsigned_integer() as i64
                             };
                             let to_index = if to_index.is_signed_integer() {
                                 to_index.as_signed_integer()
                             } else {
                                 to_index.as_unsigned_integer() as i64
                             };
                             // Dereference subject if needed
                             let subject = cur_frame.expr_values.pop_back().unwrap();
                             let deref_subject = self.store.maybe_read_ref(&subject);
                             // Slicing needs to produce a copy anyway (with the
                             // current evaluator implementation)
                             enum ValueKind{ Array, String, Message }
                             let (value_kind, array_heap_pos) = match deref_subject {
                                 Value::Array(v) => (ValueKind::Array, *v),
                                 Value::String(v) => (ValueKind::String, *v),
                                 Value::Message(v) => (ValueKind::Message, *v),
                                 _ => unreachable!()
                             };
                             if array_inclusive_index_is_invalid(&self.store, array_heap_pos, from_index) {
                                 return Err(construct_array_error(self, modules, heap, expr.from_index, array_heap_pos, from_index));
+                            }
                             if array_exclusive_index_is_invalid(&self.store, array_heap_pos, to_index) {
                                 return Err(construct_array_error(self, modules, heap, expr.to_index, array_heap_pos, to_index));
+                            }
                             // Again: would love to push directly, but rust...
                             let new_heap_pos = self.store.alloc_heap();
                             debug_assert!(self.store.heap_regions[new_heap_pos as usize].values.is_empty());
                             if to_index > from_index {
                                 let from_index = from_index as usize;
                                 let to_index = to_index as usize;
                                 let mut values = Vec::with_capacity(to_index - from_index);
                                 for idx in from_index..to_index {
                                     let value = self.store.heap_regions[array_heap_pos as usize].values[idx].clone();
                                     values.push(self.store.clone_value(value));
+                                }
                                 self.store.heap_regions[new_heap_pos as usize].values = values;
                             } // else: empty range
                             cur_frame.expr_values.push_back(match value_kind {
                                 ValueKind::Array => Value::Array(new_heap_pos),
                                 ValueKind::String => Value::String(new_heap_pos),
                                 ValueKind::Message => Value::Message(new_heap_pos),
                             });
                             // Dropping the original subject, because we don't
                             // want to drop something on the stack
                             self.store.drop_value(subject.get_heap_pos());
                         },
                         Expression::Select(expr) => {
                             let subject= cur_frame.expr_values.pop_back().unwrap();
-                            let mono_data = types.get_procedure_expression_data(&cur_frame.definition, cur_frame.monomorph_idx);
+                            let mono_data = types.get_procedure_monomorph(cur_frame.monomorph_idx);
                             let field_idx = mono_data.expr_data[expr.unique_id_in_definition as usize].field_or_monomorph_idx as u32;
                             // Note: same as above: clone if value lives on expr stack, simply
                             // refer to it if it already lives on the stack/heap.
                             let (deallocate_heap_pos, value_to_push) = match subject {
                                 Value::Ref(value_ref) => {
                                     let subject = self.store.read_ref(value_ref);
                                     let subject_heap_pos = subject.as_struct();
                                     (None, Value::Ref(ValueId::Heap(subject_heap_pos, field_idx)))
                                 },
                                 _ => {
                                     let subject_heap_pos = subject.as_struct();
                                     let subject_indexed = Value::Ref(ValueId::Heap(subject_heap_pos, field_idx));
                                     (Some(subject_heap_pos), self.store.clone_value(subject_indexed))
                                 },
                             };
                             cur_frame.expr_values.push_back(value_to_push);
                             self.store.drop_value(deallocate_heap_pos);
                         },
                         Expression::Literal(expr) => {
                             let value = match &expr.value {
                                 Literal::Null => Value::Null,
                                 Literal::True => Value::Bool(true),
                                 Literal::False => Value::Bool(false),
                                 Literal::Character(lit_value) => Value::Char(*lit_value),
                                 Literal::String(lit_value) => {
                                     let heap_pos = self.store.alloc_heap();
                                     let values = &mut self.store.heap_regions[heap_pos as usize].values;
                                     let value = lit_value.as_str();
                                     debug_assert!(values.is_empty());
                                     values.reserve(value.len());
                                     for character in value.as_bytes() {
                                         debug_assert!(character.is_ascii());
                                         values.push(Value::Char(*character as char));
+                                    }
                                     Value::String(heap_pos)
+                                }
                                 Literal::Integer(lit_value) => {
                                     use ConcreteTypePart as CTP;
-                                    let def_types = types.get_procedure_expression_data(&cur_frame.definition, cur_frame.monomorph_idx);
+                                    let def_types = types.get_procedure_monomorph(cur_frame.monomorph_idx);
                                     let concrete_type = &def_types.expr_data[expr.unique_id_in_definition as usize].expr_type;
                                     debug_assert_eq!(concrete_type.parts.len(), 1);
                                     match concrete_type.parts[0] {
                                         CTP::UInt8  => Value::UInt8(lit_value.unsigned_value as u8),
                                         CTP::UInt16 => Value::UInt16(lit_value.unsigned_value as u16),
                                         CTP::UInt32 => Value::UInt32(lit_value.unsigned_value as u32),
                                         CTP::UInt64 => Value::UInt64(lit_value.unsigned_value as u64),
                                         CTP::SInt8  => Value::SInt8(lit_value.unsigned_value as i8),
                                         CTP::SInt16 => Value::SInt16(lit_value.unsigned_value as i16),
                                         CTP::SInt32 => Value::SInt32(lit_value.unsigned_value as i32),
                                         CTP::SInt64 => Value::SInt64(lit_value.unsigned_value as i64),
                                         _ => unreachable!("got concrete type {:?} for integer literal at expr {:?}", concrete_type, expr_id),
+                                    }
+                                }
                                 Literal::Struct(lit_value) => {
                                     let heap_pos = transfer_expression_values_front_into_heap(
                                         cur_frame, &mut self.store, lit_value.fields.len()
                                     );
                                     Value::Struct(heap_pos)
+                                }
                                 Literal::Enum(lit_value) => {
                                     Value::Enum(lit_value.variant_idx as i64)
+                                }
                                 Literal::Union(lit_value) => {
                                     let heap_pos = transfer_expression_values_front_into_heap(
                                         cur_frame, &mut self.store, lit_value.values.len()
                                     );
                                     Value::Union(lit_value.variant_idx as i64, heap_pos)
+                                }
                                 Literal::Array(lit_value) => {
                                     let heap_pos = transfer_expression_values_front_into_heap(
                                         cur_frame, &mut self.store, lit_value.len()
                                     );
                                     Value::Array(heap_pos)
+                                }
                             };
                             cur_frame.expr_values.push_back(value);
                         },
                         Expression::Cast(expr) => {
-                            let mono_data = types.get_procedure_expression_data(&cur_frame.definition, cur_frame.monomorph_idx);
+                            let mono_data = types.get_procedure_monomorph(cur_frame.monomorph_idx);
                             let output_type = &mono_data.expr_data[expr.unique_id_in_definition as usize].expr_type;
                             // Typechecking reduced this to two cases: either we
                             // have casting noop (same types), or we're casting
                             // between integer/bool/char types.
                             let subject = cur_frame.expr_values.pop_back().unwrap();
                             match apply_casting(&mut self.store, output_type, &subject) {
                                 Ok(value) => cur_frame.expr_values.push_back(value),
                                 Err(msg) => {
                                     return Err(EvalError::new_error_at_expr(self, modules, heap, expr.this.upcast(), msg));
+                                }
+                            }
                             self.store.drop_value(subject.get_heap_pos());
+                        }
                         Expression::Call(expr) => {
                             // If we're dealing with a builtin we don't do any
                             // fancy shenanigans at all, just push the result.
                             match expr.method {
                                 Method::Get => {
                                     let value = cur_frame.expr_values.pop_front().unwrap();
                                     let value = self.store.maybe_read_ref(&value).clone();
                                     let port_id = if let Value::Input(port_id) = value {
                                         port_id
                                     } else {
                                         unreachable!("executor calling 'get' on value {:?}", value)
                                     };
                                     match ctx.performed_get(port_id) {
                                         Some(result) => {
                                             // We have the result. Merge the `ValueGroup` with the
                                             // stack/heap storage.
                                             debug_assert_eq!(result.values.len(), 1);
                                             result.into_stack(&mut cur_frame.expr_values, &mut self.store);
                                         },
                                         None => {
                                             // Don't have the result yet, prepare the expression to
                                             // get run again after we've received a message.
                                             cur_frame.expr_values.push_front(value.clone());
                                             cur_frame.expr_stack.push_back(ExprInstruction::EvalExpr(expr_id));
                                             return Ok(EvalContinuation::BlockGet(port_id));
+                                        }
+                                    }
                                 },
                                 Method::Put => {
                                     let port_value = cur_frame.expr_values.pop_front().unwrap();
                                     let deref_port_value = self.store.maybe_read_ref(&port_value).clone();
                                     let port_id = if let Value::Output(port_id) = deref_port_value {
                                         port_id
                                     } else {
                                         unreachable!("executor calling 'put' on value {:?}", deref_port_value)
                                     };
                                     let msg_value = cur_frame.expr_values.pop_front().unwrap();
                                     let deref_msg_value = self.store.maybe_read_ref(&msg_value).clone();
                                     if ctx.performed_put(port_id) {
                                         // We're fine, deallocate in case the expression value stack
                                         // held an owned value
                                         self.store.drop_value(msg_value.get_heap_pos());
                                     } else {
                                         // Prepare to execute again
                                         cur_frame.expr_values.push_front(msg_value);
                                         cur_frame.expr_values.push_front(port_value);
                                         cur_frame.expr_stack.push_back(ExprInstruction::EvalExpr(expr_id));
                                         let value_group = ValueGroup::from_store(&self.store, &[deref_msg_value]);
                                         return Ok(EvalContinuation::Put(port_id, value_group));
+                                    }
                                 },
                                 Method::Fires => {
                                     let port_value = cur_frame.expr_values.pop_front().unwrap();
                                     let port_value_deref = self.store.maybe_read_ref(&port_value).clone();
                                     let port_id = match port_value_deref {
                                         Value::Input(port_id) => port_id,
                                         Value::Output(port_id) => port_id,
                                         _ => unreachable!("executor calling 'fires' on value {:?}", port_value_deref),
                                     };
                                     match ctx.fires(port_id) {
                                         None => {
                                             cur_frame.expr_values.push_front(port_value);
                                             cur_frame.expr_stack.push_back(ExprInstruction::EvalExpr(expr_id));
                                             return Ok(EvalContinuation::BlockFires(port_id));
                                         },
                                         Some(value) => {
                                             cur_frame.expr_values.push_back(value);
+                                        }
+                                    }
                                 },
                                 Method::Create => {
                                     let length_value = cur_frame.expr_values.pop_front().unwrap();
                                     let length_value = self.store.maybe_read_ref(&length_value);
                                     let length = if length_value.is_signed_integer() {
                                         let length_value = length_value.as_signed_integer();
                                         if length_value < 0 {
                                             return Err(EvalError::new_error_at_expr(
                                                 self, modules, heap, expr_id,
                                                 format!("got length '{}', can only create a message with a non-negative length", length_value)
                                             ));
+                                        }
                                         length_value as u64
                                     } else {
                                         debug_assert!(length_value.is_unsigned_integer());
                                         length_value.as_unsigned_integer()
                                     };
                                     let heap_pos = self.store.alloc_heap();
                                     let values = &mut self.store.heap_regions[heap_pos as usize].values;
                                     debug_assert!(values.is_empty());
                                     values.resize(length as usize, Value::UInt8(0));
                                     cur_frame.expr_values.push_back(Value::Message(heap_pos));
                                 },
                                 Method::Length => {
                                     let value = cur_frame.expr_values.pop_front().unwrap();
                                     let value_heap_pos = value.get_heap_pos();
                                     let value = self.store.maybe_read_ref(&value);
                                     let heap_pos = match value {
                                         Value::Array(pos) => *pos,
                                         Value::String(pos) => *pos,
                                         _ => unreachable!("length(...) on {:?}", value),
                                     };
                                     let len = self.store.heap_regions[heap_pos as usize].values.len();
                                     // TODO: @PtrInt
                                     cur_frame.expr_values.push_back(Value::UInt32(len as u32));
                                     self.store.drop_value(value_heap_pos);
                                 },
                                 Method::Assert => {
                                     let value = cur_frame.expr_values.pop_front().unwrap();
                                     let value = self.store.maybe_read_ref(&value).clone();
                                     if !value.as_bool() {
                                         return Ok(EvalContinuation::BranchInconsistent)
+                                    }
                                 },
                                 Method::Print => {
                                     // Convert the runtime-variant of a string
                                     // into an actual string.
                                     let value = cur_frame.expr_values.pop_front().unwrap();
                                     let value_heap_pos = value.as_string();
                                     let elements = &self.store.heap_regions[value_heap_pos as usize].values;
                                     let mut message = String::with_capacity(elements.len());
                                     for element in elements {
                                         message.push(element.as_char());
+                                    }
                                     // Drop the heap-allocated value from the
                                     // store
                                     self.store.drop_heap_pos(value_heap_pos);
                                     println!("{}", message);
                                 },
                                 Method::UserComponent => {
                                     // This is actually handled by the evaluation
                                     // of the statement.
                                     debug_assert_eq!(heap[expr.definition].parameters().len(), cur_frame.expr_values.len());
                                     debug_assert_eq!(heap[cur_frame.position].as_new().expression, expr.this)
                                 },
                                 Method::UserFunction => {
                                     // Push a new frame. Note that all expressions have
                                     // been pushed to the front, so they're in the order
                                     // of the definition.
                                     let num_args = expr.arguments.len();
                                     // Determine stack boundaries
                                     let cur_stack_boundary = self.store.cur_stack_boundary;
                                     let new_stack_boundary = self.store.stack.len();
                                     // Push new boundary and function arguments for new frame
                                     self.store.stack.push(Value::PrevStackBoundary(cur_stack_boundary as isize));
                                     for _ in 0..num_args {
                                         let argument = self.store.read_take_ownership(cur_frame.expr_values.pop_front().unwrap());
                                         self.store.stack.push(argument);
+                                    }
                                     // Determine the monomorph index of the function we're calling
-                                    let mono_data = types.get_procedure_expression_data(&cur_frame.definition, cur_frame.monomorph_idx);
+                                    let mono_data = types.get_procedure_monomorph(cur_frame.monomorph_idx);
                                     let call_data = &mono_data.expr_data[expr.unique_id_in_definition as usize];
                                     // Push the new frame and reserve its stack size
                                     let new_frame = Frame::new(heap, expr.definition, call_data.field_or_monomorph_idx);
                                     let new_stack_size = new_frame.max_stack_size;
                                     self.frames.push(new_frame);
                                     self.store.cur_stack_boundary = new_stack_boundary;
                                     self.store.reserve_stack(new_stack_size);
                                     // To simplify the logic a little bit we will now
                                     // return and ask our caller to call us again
                                     return Ok(EvalContinuation::Stepping);
                                 },
+                            }
                         },
                         Expression::Variable(expr) => {
                             let variable = &heap[expr.declaration.unwrap()];
                             let ref_value = if expr.used_as_binding_target {
                                 Value::Binding(variable.unique_id_in_scope as StackPos)
                             } else {
                                 Value::Ref(ValueId::Stack(variable.unique_id_in_scope as StackPos))
                             };
                             cur_frame.expr_values.push_back(ref_value);
+                        }
+                    }
+                }
+            }
+        }
         debug_log!("Frame [{:?}] at {:?}", cur_frame.definition, cur_frame.position);
         if debug_enabled!() {
             debug_log!("Expression value stack (size = {}):", cur_frame.expr_values.len());
             for (_stack_idx, _stack_val) in cur_frame.expr_values.iter().enumerate() {
                 debug_log!("  [{:03}] {:?}", _stack_idx, _stack_val);
+            }
             debug_log!("Stack (size = {}):", self.store.stack.len());
             for (_stack_idx, _stack_val) in self.store.stack.iter().enumerate() {
                 debug_log!("  [{:03}] {:?}", _stack_idx, _stack_val);
+            }
             debug_log!("Heap:");
             for (_heap_idx, _heap_region) in self.store.heap_regions.iter().enumerate() {
                 let _is_free = self.store.free_regions.iter().any(|idx| *idx as usize == _heap_idx);
                 debug_log!("  [{:03}] in_use: {}, len: {}, vals: {:?}", _heap_idx, !_is_free, _heap_region.values.len(), &_heap_region.values);
+            }
+        }
         // No (more) expressions to evaluate. So evaluate statement (that may
         // depend on the result on the last evaluated expression(s))
         let stmt = &heap[cur_frame.position];
         let return_value = match stmt {
             Statement::Block(stmt) => {
                 debug_assert!(stmt.statements.is_empty() || stmt.next == stmt.statements[0]);
                 cur_frame.position = stmt.next;
                 Ok(EvalContinuation::Stepping)
             },
             Statement::EndBlock(stmt) => {
                 let block = &heap[stmt.start_block];
                 self.store.clear_stack(block.first_unique_id_in_scope as usize);
                 cur_frame.position = stmt.next;
                 Ok(EvalContinuation::Stepping)
             },
             Statement::Local(stmt) => {
                 match stmt {
                     LocalStatement::Memory(stmt) => {
                         let variable = &heap[stmt.variable];
                         self.store.write(ValueId::Stack(variable.unique_id_in_scope as u32), Value::Unassigned);
                         cur_frame.position = stmt.next;
                         Ok(EvalContinuation::Stepping)
                     },
                     LocalStatement::Channel(stmt) => {
                         // Need to create a new channel by requesting it from
                         // the runtime.
                         match ctx.created_channel() {
                             None => {
                                 // No channel is pending. So request one
                                 Ok(EvalContinuation::NewChannel)
                             },
                             Some((put_port, get_port)) => {
                                 self.store.write(ValueId::Stack(heap[stmt.from].unique_id_in_scope as u32), put_port);
                                 self.store.write(ValueId::Stack(heap[stmt.to].unique_id_in_scope as u32), get_port);
                                 cur_frame.position = stmt.next;
                                 Ok(EvalContinuation::Stepping)
+                            }
+                        }
+                    }
+                }
             },
             Statement::Labeled(stmt) => {
                 cur_frame.position = stmt.body;
                 Ok(EvalContinuation::Stepping)
             },
             Statement::If(stmt) => {
                 debug_assert_eq!(cur_frame.expr_values.len(), 1, "expected one expr value for if statement");
                 let test_value = cur_frame.expr_values.pop_back().unwrap();
                 let test_value = self.store.maybe_read_ref(&test_value).as_bool();
                 if test_value {
                     cur_frame.position = stmt.true_body.upcast();
                 } else if let Some(false_body) = stmt.false_body {
                     cur_frame.position = false_body.upcast();
                 } else {
                     // Not true, and no false body
                     cur_frame.position = stmt.end_if.upcast();
+                }
                 Ok(EvalContinuation::Stepping)
             },
             Statement::EndIf(stmt) => {
                 cur_frame.position = stmt.next;
                 Ok(EvalContinuation::Stepping)
             },
             Statement::While(stmt) => {
                 debug_assert_eq!(cur_frame.expr_values.len(), 1, "expected one expr value for while statement");
                 let test_value = cur_frame.expr_values.pop_back().unwrap();
                 let test_value = self.store.maybe_read_ref(&test_value).as_bool();
                 if test_value {
                     cur_frame.position = stmt.body.upcast();
                 } else {
                     cur_frame.position = stmt.end_while.upcast();
+                }
                 Ok(EvalContinuation::Stepping)
             },
             Statement::EndWhile(stmt) => {
                 cur_frame.position = stmt.next;
                 Ok(EvalContinuation::Stepping)
             },
             Statement::Break(stmt) => {
                 cur_frame.position = stmt.target.unwrap().upcast();
                 Ok(EvalContinuation::Stepping)
             },
             Statement::Continue(stmt) => {
                 cur_frame.position = stmt.target.unwrap().upcast();
                 Ok(EvalContinuation::Stepping)
             },
             Statement::Synchronous(stmt) => {
                 cur_frame.position = stmt.body.upcast();
                 Ok(EvalContinuation::SyncBlockStart)
             },
             Statement::EndSynchronous(stmt) => {
                 cur_frame.position = stmt.next;
                 Ok(EvalContinuation::SyncBlockEnd)
             },
             Statement::Fork(stmt) => {
                 if stmt.right_body.is_none() {
                     // No reason to fork
                     cur_frame.position = stmt.left_body.upcast();
                 } else {
                     // Need to fork
                     if let Some(go_left) = ctx.performed_fork() {
                         // Runtime has created a fork
                         if go_left {
                             cur_frame.position = stmt.left_body.upcast();
                         } else {
                             cur_frame.position = stmt.right_body.unwrap().upcast();
+                        }
                     } else {
                         // Request the runtime to create a fork of the current
                         // branch
                         return Ok(EvalContinuation::NewFork);
+                    }
+                }
                 Ok(EvalContinuation::Stepping)
             },
             Statement::EndFork(stmt) => {
                 cur_frame.position = stmt.next;
                 Ok(EvalContinuation::Stepping)
+            }
             Statement::Return(_stmt) => {
                 debug_assert!(heap[cur_frame.definition].is_function());
                 debug_assert_eq!(cur_frame.expr_values.len(), 1, "expected one expr value for return statement");
                 // The preceding frame has executed a call, so is expecting the
                 // return expression on its expression value stack. Note that
                 // we may be returning a reference to something on our stack,
                 // so we need to read that value and clone it.
                 let return_value = cur_frame.expr_values.pop_back().unwrap();
                 let return_value = match return_value {
                     Value::Ref(value_id) => self.store.read_copy(value_id),
                     _ => return_value,
                 };
                 // Pre-emptively pop our stack frame
                 self.frames.pop();
                 // Clean up our section of the stack
                 self.store.clear_stack(0);
                 self.store.stack.truncate(self.store.cur_stack_boundary + 1);
                 let prev_stack_idx = self.store.stack.pop().unwrap().as_stack_boundary();
                 // TODO: Temporary hack for testing, remove at some point
                 if self.frames.is_empty() {
                     debug_assert!(prev_stack_idx == -1);
                     debug_assert!(self.store.stack.len() == 0);
                     self.store.stack.push(return_value);
                     return Ok(EvalContinuation::ComponentTerminated);
+                }
                 debug_assert!(prev_stack_idx >= 0);
                 // Return to original state of stack frame
                 self.store.cur_stack_boundary = prev_stack_idx as usize;
                 let cur_frame = self.frames.last_mut().unwrap();
                 cur_frame.expr_values.push_back(return_value);
                 // We just returned to the previous frame, which might be in
                 // the middle of evaluating expressions for a particular
                 // statement. So we don't want to enter the code below.
                 return Ok(EvalContinuation::Stepping);
             },
             Statement::Goto(stmt) => {
                 cur_frame.position = stmt.target.unwrap().upcast();
                 Ok(EvalContinuation::Stepping)
             },
             Statement::New(stmt) => {
                 let call_expr = &heap[stmt.expression];
                 debug_assert!(heap[call_expr.definition].is_component());
                 debug_assert_eq!(
                     cur_frame.expr_values.len(), heap[call_expr.definition].parameters().len(),
                     "mismatch in expr stack size and number of arguments for new statement"
                 );
-                let mono_data = types.get_procedure_expression_data(&cur_frame.definition, cur_frame.monomorph_idx);
+                let mono_data = types.get_procedure_monomorph(cur_frame.monomorph_idx);
                 let expr_data = &mono_data.expr_data[call_expr.unique_id_in_definition as usize];
                 // Note that due to expression value evaluation they exist in
                 // reverse order on the stack.
                 // TODO: Revise this code, keep it as is to be compatible with current runtime
                 let mut args = Vec::new();
                 while let Some(value) = cur_frame.expr_values.pop_front() {
                     args.push(value);
+                }
                 // Construct argument group, thereby copying heap regions
                 let argument_group = ValueGroup::from_store(&self.store, &args);
                 // println!("Creating {} with\n{:#?}", heap[call_expr.definition].identifier().value.as_str(), argument_group);
                 // Clear any heap regions
                 for arg in &args {
                     self.store.drop_value(arg.get_heap_pos());
+                }
                 cur_frame.position = stmt.next;
                 Ok(EvalContinuation::NewComponent(call_expr.definition, expr_data.field_or_monomorph_idx, argument_group))
             },
             Statement::Expression(stmt) => {
                 // The expression has just been completely evaluated. Some
                 // values might have remained on the expression value stack.
                 // cur_frame.expr_values.clear(); PROPER CLEARING
                 cur_frame.position = stmt.next;
                 Ok(EvalContinuation::Stepping)
             },
         };
         assert!(
             cur_frame.expr_values.is_empty(),
             "This is a debugging assertion that will fail if you perform expressions without \
             assigning to anything. This should be completely valid, and this assertion should be \
             replaced by something that clears the expression values if needed, but I'll keep this \
             in for now for debugging purposes."
         );
         // If the next statement requires evaluating expressions then we push
         // these onto the expression stack. This way we will evaluate this
         // stack in the next loop, then evaluate the statement using the result
         // from the expression evaluation.
         if !cur_frame.position.is_invalid() {
             let stmt = &heap[cur_frame.position];
             match stmt {
                 Statement::If(stmt) => cur_frame.prepare_single_expression(heap, stmt.test),
                 Statement::While(stmt) => cur_frame.prepare_single_expression(heap, stmt.test),
                 Statement::Return(stmt) => {
                     debug_assert_eq!(stmt.expressions.len(), 1); // TODO: @ReturnValues
                     cur_frame.prepare_single_expression(heap, stmt.expressions[0]);
                 },
                 Statement::New(stmt) => {
                     // Note that we will end up not evaluating the call itself.
                     // Rather we will evaluate its expressions and then
                     // instantiate the component upon reaching the "new" stmt.
                     let call_expr = &heap[stmt.expression];
                     cur_frame.prepare_multiple_expressions(heap, &call_expr.arguments);
                 },
                 Statement::Expression(stmt) => {
                     cur_frame.prepare_single_expression(heap, stmt.expression);
+                }
                 _ => {},
+            }
+        }
         return_value
+    }
     /// Constructs an error at the current expression that lives at the top of
     /// the expression stack. Falls back to constructing an error at the current
     /// statement if there is no expression.
     pub(crate) fn new_error_at_expr(&self, modules: &[Module], heap: &Heap, error_message: String) -> EvalError {
         let last_frame = self.frames.last().unwrap();
         for instruction in last_frame.expr_stack.iter().rev() {
             if let ExprInstruction::EvalExpr(expression_id) = instruction {
                 return EvalError::new_error_at_expr(
                     self, modules, heap, *expression_id, error_message
                 );
+            }
+        }
         // If here then expression stack was empty (cannot have just rotate
         // instructions)
         panic!("attempted to construct evaluation error without any expressions to evaluate in frame");
+    }
+}
@@ \ No newline at end of file @@

src/protocol/mod.rs

➞

Show inline comments

 mod arena;
 pub(crate) mod eval;
 pub(crate) mod input_source;
 mod parser;
 #[cfg(test)] mod tests;
 pub(crate) mod ast;
 pub(crate) mod ast_printer;
 use std::sync::Mutex;
 use crate::collections::{StringPool, StringRef};
 use crate::protocol::ast::*;
 use crate::protocol::eval::*;
 use crate::protocol::input_source::*;
 use crate::protocol::parser::*;
 use crate::protocol::type_table::*;
 /// A protocol description module
 pub struct Module {
     pub(crate) source: InputSource,
     pub(crate) root_id: RootId,
     pub(crate) name: Option<StringRef<'static>>,
+}
 /// Description of a protocol object, used to configure new connectors.
 #[repr(C)]
 pub struct ProtocolDescription {
     pub(crate) modules: Vec<Module>,
     pub(crate) heap: Heap,
     pub(crate) types: TypeTable,
     pub(crate) pool: Mutex<StringPool>,
+}
 #[derive(Debug, Clone)]
 pub(crate) struct ComponentState {
     pub(crate) prompt: Prompt,
+}
 #[derive(Debug)]
 pub enum ComponentCreationError {
     ModuleDoesntExist,
     DefinitionDoesntExist,
     DefinitionNotComponent,
     InvalidNumArguments,
     InvalidArgumentType(usize),
     UnownedPort,
     InSync,
+}
 impl std::fmt::Debug for ProtocolDescription {
     fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
         write!(f, "(An opaque protocol description)")
+    }
+}
 impl ProtocolDescription {
     pub fn parse(buffer: &[u8]) -> Result<Self, String> {
         let source = InputSource::new(String::new(), Vec::from(buffer));
         let mut parser = Parser::new();
         parser.feed(source).expect("failed to feed source");
         if let Err(err) = parser.parse() {
             println!("ERROR:\n{}", err);
             return Err(format!("{}", err))
+        }
         debug_assert_eq!(parser.modules.len(), 1, "only supporting one module here for now");
         let modules: Vec<Module> = parser.modules.into_iter()
             .map(|module| Module{
                 source: module.source,
                 root_id: module.root_id,
                 name: module.name.map(|(_, name)| name)
             })
             .collect();
         return Ok(ProtocolDescription {
             modules,
             heap: parser.heap,
             types: parser.type_table,
             pool: Mutex::new(parser.string_pool),
         });
+    }
     pub(crate) fn new_component(
         &self, module_name: &[u8], identifier: &[u8], arguments: ValueGroup
     ) -> Result<Prompt, ComponentCreationError> {
         // Find the module in which the definition can be found
         let module_root = self.lookup_module_root(module_name);
         if module_root.is_none() {
             return Err(ComponentCreationError::ModuleDoesntExist);
+        }
         let module_root = module_root.unwrap();
         let root = &self.heap[module_root];
         let definition_id = root.get_definition_ident(&self.heap, identifier);
         if definition_id.is_none() {
             return Err(ComponentCreationError::DefinitionDoesntExist);
+        }
         let definition_id = definition_id.unwrap();
         let definition = &self.heap[definition_id];
         if !definition.is_component() {
         let ast_definition = &self.heap[definition_id];
         if !ast_definition.is_component() {
             return Err(ComponentCreationError::DefinitionNotComponent);
+        }
         // Make sure that the types of the provided value group matches that of
         // the expected types.
         let definition = definition.as_component();
         if !definition.poly_vars.is_empty() {
         let ast_definition = ast_definition.as_component();
         if !ast_definition.poly_vars.is_empty() {
             return Err(ComponentCreationError::DefinitionNotComponent);
+        }
         // - check number of arguments
         let expr_data = self.types.get_procedure_expression_data(&definition_id, 0);
         if expr_data.arg_types.len() != arguments.values.len() {
         // - check number of arguments by retrieving the one instantiated
         //   monomorph
         let concrete_type = ConcreteType{ parts: vec![ConcreteTypePart::Component(definition_id, 0)] };
         let mono_index = self.types.get_procedure_monomorph_index(&definition_id, &concrete_type.parts).unwrap();
         let mono_type = self.types.get_procedure_monomorph(mono_index);
         if mono_type.arg_types.len() != arguments.values.len() {
             return Err(ComponentCreationError::InvalidNumArguments);
+        }
         // - for each argument try to make sure the types match
         for arg_idx in 0..arguments.values.len() {
-            let expected_type = &expr_data.arg_types[arg_idx];
+            let expected_type = &mono_type.arg_types[arg_idx];
             let provided_value = &arguments.values[arg_idx];
             if !self.verify_same_type(expected_type, 0, &arguments, provided_value) {
                 return Err(ComponentCreationError::InvalidArgumentType(arg_idx));
+            }
+        }
         // By now we're sure that all of the arguments are correct. So create
         // the connector.
         return Ok(Prompt::new(&self.types, &self.heap, definition_id, 0, arguments));
+    }
     fn lookup_module_root(&self, module_name: &[u8]) -> Option<RootId> {
         for module in self.modules.iter() {
             match &module.name {
                 Some(name) => if name.as_bytes() == module_name {
                     return Some(module.root_id);
                 },
                 None => if module_name.is_empty() {
                     return Some(module.root_id);
+                }
+            }
+        }
         return None;
+    }
     fn verify_same_type(&self, expected: &ConcreteType, expected_idx: usize, arguments: &ValueGroup, argument: &Value) -> bool {
         use ConcreteTypePart as CTP;
         match &expected.parts[expected_idx] {
             CTP::Void | CTP::Message | CTP::Slice | CTP::Function(_, _) | CTP::Component(_, _) => unreachable!(),
             CTP::Bool => if let Value::Bool(_) = argument { true } else { false },
             CTP::UInt8 => if let Value::UInt8(_) = argument { true } else { false },
             CTP::UInt16 => if let Value::UInt16(_) = argument { true } else { false },
             CTP::UInt32 => if let Value::UInt32(_) = argument { true } else { false },
             CTP::UInt64 => if let Value::UInt64(_) = argument { true } else { false },
             CTP::SInt8 => if let Value::SInt8(_) = argument { true } else { false },
             CTP::SInt16 => if let Value::SInt16(_) = argument { true } else { false },
             CTP::SInt32 => if let Value::SInt32(_) = argument { true } else { false },
             CTP::SInt64 => if let Value::SInt64(_) = argument { true } else { false },
             CTP::Character => if let Value::Char(_) = argument { true } else { false },
             CTP::String => {
                 // Match outer string type and embedded character types
                 if let Value::String(heap_pos) = argument {
                     for element in &arguments.regions[*heap_pos as usize] {
                         if let Value::Char(_) = element {} else {
                             return false;
+                        }
+                    }
                 } else {
                     return false;
+                }
                 return true;
             },
             CTP::Array => {
                 if let Value::Array(heap_pos) = argument {
                     let heap_pos = *heap_pos;
                     for element in &arguments.regions[heap_pos as usize] {
                         if !self.verify_same_type(expected, expected_idx + 1, arguments, element) {
                             return false;
+                        }
+                    }
                     return true;
                 } else {
                     return false;
+                }
             },
             CTP::Input => if let Value::Input(_) = argument { true } else { false },
             CTP::Output => if let Value::Output(_) = argument { true } else { false },
             CTP::Tuple(_) => todo!("implement full type checking on user-supplied arguments"),
             CTP::Instance(definition_id, _num_embedded) => {
                 let definition = self.types.get_base_definition(definition_id).unwrap();
                 match &definition.definition {
                     DefinedTypeVariant::Enum(definition) => {
                         if let Value::Enum(variant_value) = argument {
                             let is_valid = definition.variants.iter()
                                 .any(|v| v.value == *variant_value);
                             return is_valid;
+                        }
                     },
                     _ => todo!("implement full type checking on user-supplied arguments"),
+                }
                 return false;
             },
+        }
+    }
+}
 pub trait RunContext {
     fn performed_put(&mut self, port: PortId) -> bool;
     fn performed_get(&mut self, port: PortId) -> Option<ValueGroup>; // None if still waiting on message
     fn fires(&mut self, port: PortId) -> Option<Value>; // None if not yet branched
     fn performed_fork(&mut self) -> Option<bool>; // None if not yet forked
     fn created_channel(&mut self) -> Option<(Value, Value)>; // None if not yet prepared
+}

src/protocol/parser/pass_typing.rs

➞

Show inline comments

 /// pass_typing
 ///
 /// Performs type inference and type checking. Type inference is implemented by
 /// applying constraints on (sub)trees of types. During this process the
 /// resolver takes the `ParserType` structs (the representation of the types
 /// written by the programmer), converts them to `InferenceType` structs (the
 /// temporary data structure used during type inference) and attempts to arrive
 /// at `ConcreteType` structs (the representation of a fully checked and
 /// validated type).
 ///
 /// The resolver will visit every statement and expression relevant to the
 /// procedure and insert and determine its initial type based on context (e.g. a
 /// return statement's expression must match the function's return type, an
 /// if statement's test expression must evaluate to a boolean). When all are
 /// visited we attempt to make progress in evaluating the types. Whenever a type
 /// is progressed we queue the related expressions for further type progression.
 /// Once no more expressions are in the queue the algorithm is finished. At this
 /// point either all types are inferred (or can be trivially implicitly
 /// determined), or we have incomplete types. In the latter case we return an
 /// error.
 ///
 /// TODO: Needs a thorough rewrite:
 ///  0. polymorph_progress is intentionally broken at the moment. Make it work
 ///     again and use a normal VecSomething.
 ///  1. The foundation for doing all of the work with predetermined indices
 ///     instead of with HashMaps is there, but it is not really used because of
 ///     time constraints. When time is available, rewrite the system such that
 ///     AST IDs are not needed, and only indices into arrays are used.
 ///  2. We're doing a lot of extra work. It seems better to apply the initial
 ///     type based on expression parents, and immediately apply forced
 ///     constraints (arg to a fires() call must be port-like). All of the \
 ///     progress_xxx calls should then only be concerned with "transmitting"
 ///     type inference across their parent/child expressions.
 ///  3. Remove the `msg` type?
 ///  4. Disallow certain types in certain operations (e.g. `Void`).
 macro_rules! debug_log_enabled {
     () => { false };
+}
 macro_rules! debug_log {
     ($format:literal) => {
         enabled_debug_print!(false, "types", $format);
     };
     ($format:literal, $($args:expr),*) => {
         enabled_debug_print!(false, "types", $format, $($args),*);
     };
+}
 use std::collections::{HashMap, HashSet};
 use crate::collections::DequeSet;
 use crate::protocol::ast::*;
 use crate::protocol::input_source::ParseError;
 use crate::protocol::parser::ModuleCompilationPhase;
 use crate::protocol::parser::type_table::*;
 use crate::protocol::parser::token_parsing::*;
 use super::visitor::{
     STMT_BUFFER_INIT_CAPACITY,
     EXPR_BUFFER_INIT_CAPACITY,
     Ctx,
     Visitor,
     VisitorResult
 };
 const VOID_TEMPLATE: [InferenceTypePart; 1] = [ InferenceTypePart::Void ];
 const MESSAGE_TEMPLATE: [InferenceTypePart; 2] = [ InferenceTypePart::Message, InferenceTypePart::UInt8 ];
 const BOOL_TEMPLATE: [InferenceTypePart; 1] = [ InferenceTypePart::Bool ];
 const CHARACTER_TEMPLATE: [InferenceTypePart; 1] = [ InferenceTypePart::Character ];
 const STRING_TEMPLATE: [InferenceTypePart; 2] = [ InferenceTypePart::String, InferenceTypePart::Character ];
 const NUMBERLIKE_TEMPLATE: [InferenceTypePart; 1] = [ InferenceTypePart::NumberLike ];
 const INTEGERLIKE_TEMPLATE: [InferenceTypePart; 1] = [ InferenceTypePart::IntegerLike ];
 const ARRAY_TEMPLATE: [InferenceTypePart; 2] = [ InferenceTypePart::Array, InferenceTypePart::Unknown ];
 const SLICE_TEMPLATE: [InferenceTypePart; 2] = [ InferenceTypePart::Slice, InferenceTypePart::Unknown ];
 const ARRAYLIKE_TEMPLATE: [InferenceTypePart; 2] = [ InferenceTypePart::ArrayLike, InferenceTypePart::Unknown ];
 /// TODO: @performance Turn into PartialOrd+Ord to simplify checks
 #[derive(Debug, Clone, Eq, PartialEq)]
 pub(crate) enum InferenceTypePart {
     // When we infer types of AST elements that support polymorphic arguments,
     // then we might have the case that multiple embedded types depend on the
     // polymorphic type (e.g. func bla(T a, T[] b) -> T[][]). If we can infer
     // the type in one place (e.g. argument a), then we may propagate this
     // information to other types (e.g. argument b and the return type). For
     // this reason we place markers in the `InferenceType` instances such that
     // we know which part of the type was originally a polymorphic argument.
     Marker(u32),
     // Completely unknown type, needs to be inferred
     Unknown,
     // Partially known type, may be inferred to to be the appropriate related
     // type.
     // IndexLike,      // index into array/slice
     NumberLike,     // any kind of integer/float
     IntegerLike,    // any kind of integer
     ArrayLike,      // array or slice. Note that this must have a subtype
     PortLike,       // input or output port
     // Special types that cannot be instantiated by the user
     Void, // For builtin functions that do not return anything
     // Concrete types without subtypes
     Bool,
     UInt8,
     UInt16,
     UInt32,
     UInt64,
     SInt8,
     SInt16,
     SInt32,
     SInt64,
     Character,
     String,
     // One subtype
     Message,
     Array,
     Slice,
     Input,
     Output,
     // Tuple with any number of subtypes (for practical reasons 1 element is impossible)
     Tuple(u32),
     // A user-defined type with any number of subtypes
     Instance(DefinitionId, u32)
+}
 impl InferenceTypePart {
     fn is_marker(&self) -> bool {
         match self {
             InferenceTypePart::Marker(_) => true,
             _ => false,
+        }
+    }
     /// Checks if the type is concrete, markers are interpreted as concrete
     /// types.
     fn is_concrete(&self) -> bool {
         use InferenceTypePart as ITP;
         match self {
             ITP::Unknown | ITP::NumberLike |
             ITP::IntegerLike | ITP::ArrayLike | ITP::PortLike => false,
             _ => true
+        }
+    }
     fn is_concrete_number(&self) -> bool {
         use InferenceTypePart as ITP;
         match self {
             ITP::UInt8 | ITP::UInt16 | ITP::UInt32 | ITP::UInt64 |
             ITP::SInt8 | ITP::SInt16 | ITP::SInt32 | ITP::SInt64 => true,
             _ => false,
+        }
+    }
     fn is_concrete_integer(&self) -> bool {
         use InferenceTypePart as ITP;
         match self {
             ITP::UInt8 | ITP::UInt16 | ITP::UInt32 | ITP::UInt64 |
             ITP::SInt8 | ITP::SInt16 | ITP::SInt32 | ITP::SInt64 => true,
             _ => false,
+        }
+    }
     fn is_concrete_arraylike(&self) -> bool {
         use InferenceTypePart as ITP;
         match self {
             ITP::Array | ITP::Slice | ITP::String | ITP::Message => true,
             _ => false,
+        }
+    }
     fn is_concrete_port(&self) -> bool {
         use InferenceTypePart as ITP;
         match self {
             ITP::Input | ITP::Output => true,
             _ => false,
+        }
+    }
     /// Checks if a part is less specific than the argument. Only checks for
     /// single-part inference (i.e. not the replacement of an `Unknown` variant
     /// with the argument)
     fn may_be_inferred_from(&self, arg: &InferenceTypePart) -> bool {
         use InferenceTypePart as ITP;
         (*self == ITP::IntegerLike && arg.is_concrete_integer()) ||
         (*self == ITP::NumberLike && (arg.is_concrete_number() || *arg == ITP::IntegerLike)) ||
         (*self == ITP::ArrayLike && arg.is_concrete_arraylike()) ||
         (*self == ITP::PortLike && arg.is_concrete_port())
+    }
     /// Checks if a part is more specific
     /// Returns the change in "iteration depth" when traversing this particular
     /// part. The iteration depth is used to traverse the tree in a linear
     /// fashion. It is basically `number_of_subtypes - 1`
     fn depth_change(&self) -> i32 {
         use InferenceTypePart as ITP;
         match &self {
             ITP::Unknown | ITP::NumberLike | ITP::IntegerLike |
             ITP::Void | ITP::Bool |
             ITP::UInt8 | ITP::UInt16 | ITP::UInt32 | ITP::UInt64 |
             ITP::SInt8 | ITP::SInt16 | ITP::SInt32 | ITP::SInt64 |
             ITP::Character => {
                 -1
             },
             ITP::Marker(_) |
             ITP::ArrayLike | ITP::Message | ITP::Array | ITP::Slice |
             ITP::PortLike | ITP::Input | ITP::Output | ITP::String => {
                 // One subtype, so do not modify depth
             },
             ITP::Tuple(num) | ITP::Instance(_, num) => {
                 (*num as i32) - 1
+            }
+        }
+    }
+}
 #[derive(Debug, Clone)]
 struct InferenceType {
     has_marker: bool,
     is_done: bool,
     parts: Vec<InferenceTypePart>,
+}
 impl InferenceType {
     /// Generates a new InferenceType. The two boolean flags will be checked in
     /// debug mode.
     fn new(has_marker: bool, is_done: bool, parts: Vec<InferenceTypePart>) -> Self {
         if cfg!(debug_assertions) {
             debug_assert!(!parts.is_empty());
             let parts_body_marker = parts.iter().any(|v| v.is_marker());
             debug_assert_eq!(has_marker, parts_body_marker);
             let parts_done = parts.iter().all(|v| v.is_concrete());
             debug_assert_eq!(is_done, parts_done, "{:?}", parts);
+        }
         Self{ has_marker, is_done, parts }
+    }
     /// Replaces a type subtree with the provided subtree. The caller must make
     /// sure the the replacement is a well formed type subtree.
     fn replace_subtree(&mut self, start_idx: usize, with: &[InferenceTypePart]) {
         let end_idx = Self::find_subtree_end_idx(&self.parts, start_idx);
         debug_assert_eq!(with.len(), Self::find_subtree_end_idx(with, 0));
         self.parts.splice(start_idx..end_idx, with.iter().cloned());
         self.recompute_is_done();
+    }
     // TODO: @performance, might all be done inline in the type inference methods
     fn recompute_is_done(&mut self) {
         self.is_done = self.parts.iter().all(|v| v.is_concrete());
+    }
     /// Seeks a body marker starting at the specified position. If a marker is
     /// found then its value and the index of the type subtree that follows it
     /// is returned.
     fn find_marker(&self, mut start_idx: usize) -> Option<(u32, usize)> {
         while start_idx < self.parts.len() {
             if let InferenceTypePart::Marker(marker) = &self.parts[start_idx] {
                 return Some((*marker, start_idx + 1))
+            }
             start_idx += 1;
+        }
         None
+    }
     /// Returns an iterator over all body markers and the partial type tree that
     /// follows those markers. If it is a problem that `InferenceType` is
     /// borrowed by the iterator, then use `find_body_marker`.
     fn marker_iter(&self) -> InferenceTypeMarkerIter {
         InferenceTypeMarkerIter::new(&self.parts)
+    }
     /// Given that the `parts` are a depth-first serialized tree of types, this
     /// function finds the subtree anchored at a specific node. The returned
     /// index is exclusive.
     fn find_subtree_end_idx(parts: &[InferenceTypePart], start_idx: usize) -> usize {
         let mut depth = 1;
         let mut idx = start_idx;
         while idx < parts.len() {
             depth += parts[idx].depth_change();
             if depth == 0 {
                 return idx + 1;
+            }
             idx += 1;
+        }
         // If here, then the inference type is malformed
         unreachable!("Malformed type: {:?}", parts);
+    }
     /// Call that attempts to infer the part at `to_infer.parts[to_infer_idx]`
     /// using the subtree at `template.parts[template_idx]`. Will return
     /// `Some(depth_change_due_to_traversal)` if type inference has been
     /// applied. In this case the indices will also be modified to point to the
     /// next part in both templates. If type inference has not (or: could not)
     /// be applied then `None` will be returned. Note that this might mean that
     /// the types are incompatible.
     ///
     /// As this is a helper functions, some assumptions: the parts are not
     /// exactly equal, and neither of them contains a marker. Also: only the
     /// `to_infer` parts are checked for inference. It might be that this
     /// function returns `None`, but that that `template` is still compatible
     /// with `to_infer`, e.g. when `template` has an `Unknown` part.
     fn infer_part_for_single_type(
         to_infer: &mut InferenceType, to_infer_idx: &mut usize,
         template_parts: &[InferenceTypePart], template_idx: &mut usize,
     ) -> Option<i32> {
         use InferenceTypePart as ITP;
         let to_infer_part = &to_infer.parts[*to_infer_idx];
         let template_part = &template_parts[*template_idx];
         // Check for programmer mistakes
         debug_assert_ne!(to_infer_part, template_part);
         debug_assert!(!to_infer_part.is_marker(), "marker encountered in 'infer part'");
         debug_assert!(!template_part.is_marker(), "marker encountered in 'template part'");
         // Inference of a somewhat-specified type
         if to_infer_part.may_be_inferred_from(template_part) {
             let depth_change = to_infer_part.depth_change();
             debug_assert_eq!(depth_change, template_part.depth_change());
             to_infer.parts[*to_infer_idx] = template_part.clone();
             *to_infer_idx += 1;
             *template_idx += 1;
             return Some(depth_change);
+        }
         // Inference of a completely unknown type
         if *to_infer_part == ITP::Unknown {
             // template part is different, so cannot be unknown, hence copy the
             // entire subtree. Make sure not to copy markers.
             let template_end_idx = Self::find_subtree_end_idx(template_parts, *template_idx);
             to_infer.parts[*to_infer_idx] = template_parts[*template_idx].clone(); // first element
             *to_infer_idx += 1;
             for template_idx in *template_idx + 1..template_end_idx {
                 let template_part = &template_parts[template_idx];
                 if !template_part.is_marker() {
                     to_infer.parts.insert(*to_infer_idx, template_part.clone());
                     *to_infer_idx += 1;
+                }
+            }
             *template_idx = template_end_idx;
             // Note: by definition the LHS was Unknown and the RHS traversed a
             // full subtree.
             return Some(-1);
+        }
         None
+    }
     /// Call that checks if the `to_check` part is compatible with the `infer`
     /// part. This is essentially a copy of `infer_part_for_single_type`, but
     /// without actually copying the type parts.
     fn check_part_for_single_type(
         to_check_parts: &[InferenceTypePart], to_check_idx: &mut usize,
         template_parts: &[InferenceTypePart], template_idx: &mut usize
     ) -> Option<i32> {
         use InferenceTypePart as ITP;
         let to_check_part = &to_check_parts[*to_check_idx];
         let template_part = &template_parts[*template_idx];
         // Checking programmer errors
         debug_assert_ne!(to_check_part, template_part);
         debug_assert!(!to_check_part.is_marker(), "marker encountered in 'to_check part'");
         debug_assert!(!template_part.is_marker(), "marker encountered in 'template part'");
         if to_check_part.may_be_inferred_from(template_part) {
             let depth_change = to_check_part.depth_change();
             debug_assert_eq!(depth_change, template_part.depth_change());
             *to_check_idx += 1;
             *template_idx += 1;
             return Some(depth_change);
+        }
         if *to_check_part == ITP::Unknown {
             *to_check_idx += 1;
             *template_idx = Self::find_subtree_end_idx(template_parts, *template_idx);
             // By definition LHS and RHS had depth change of -1
             return Some(-1);
+        }
         None
+    }
     /// Attempts to infer types between two `InferenceType` instances. This
     /// function is unsafe as it accepts pointers to work around Rust's
     /// borrowing rules. The caller must ensure that the pointers are distinct.
     unsafe fn infer_subtrees_for_both_types(
         type_a: *mut InferenceType, start_idx_a: usize,
         type_b: *mut InferenceType, start_idx_b: usize
     ) -> DualInferenceResult {
         debug_assert!(!std::ptr::eq(type_a, type_b), "encountered pointers to the same inference type");
         let type_a = &mut *type_a;
         let type_b = &mut *type_b;
         let mut modified_a = false;
         let mut modified_b = false;
         let mut idx_a = start_idx_a;
         let mut idx_b = start_idx_b;
         let mut depth = 1;
         while depth > 0 {
             // Advance indices if we encounter markers or equal parts
             let part_a = &type_a.parts[idx_a];
             let part_b = &type_b.parts[idx_b];
             if part_a == part_b {
                 let depth_change = part_a.depth_change();
                 depth += depth_change;
                 debug_assert_eq!(depth_change, part_b.depth_change());
                 idx_a += 1;
                 idx_b += 1;
                 continue;
+            }
             if part_a.is_marker() { idx_a += 1; continue; }
             if part_b.is_marker() { idx_b += 1; continue; }
             // Types are not equal and are both not markers
             if let Some(depth_change) = Self::infer_part_for_single_type(type_a, &mut idx_a, &type_b.parts, &mut idx_b) {
                 depth += depth_change;
                 modified_a = true;
                 continue;
+            }
             if let Some(depth_change) = Self::infer_part_for_single_type(type_b, &mut idx_b, &type_a.parts, &mut idx_a) {
                 depth += depth_change;
                 modified_b = true;
                 continue;
+            }
             // Types can not be inferred in any way: types must be incompatible
             return DualInferenceResult::Incompatible;
+        }
         if modified_a { type_a.recompute_is_done(); }
         if modified_b { type_b.recompute_is_done(); }
         // If here then we completely inferred the subtrees.
         match (modified_a, modified_b) {
             (false, false) => DualInferenceResult::Neither,
             (false, true) => DualInferenceResult::Second,
             (true, false) => DualInferenceResult::First,
             (true, true) => DualInferenceResult::Both
+        }
+    }
     /// Attempts to infer the first subtree based on the template. Like
     /// `infer_subtrees_for_both_types`, but now only applying inference to
     /// `to_infer` based on the type information in `template`.
     ///
     /// The `forced_template` flag controls whether `to_infer` is considered
     /// valid if it is more specific then the template. When `forced_template`
     /// is false, then as long as the `to_infer` and `template` types are
     /// compatible the inference will succeed. If `forced_template` is true,
     /// then `to_infer` MUST be less specific than `template` (e.g.
     /// `IntegerLike` is less specific than `UInt32`)
     fn infer_subtree_for_single_type(
         to_infer: &mut InferenceType, mut to_infer_idx: usize,
         template: &[InferenceTypePart], mut template_idx: usize,
         forced_template: bool,
     ) -> SingleInferenceResult {
         let mut modified = false;
         let mut depth = 1;
         while depth > 0 {
             let to_infer_part = &to_infer.parts[to_infer_idx];
             let template_part = &template[template_idx];
             if to_infer_part == template_part {
                 let depth_change = to_infer_part.depth_change();
                 depth += depth_change;
                 debug_assert_eq!(depth_change, template_part.depth_change());
                 to_infer_idx += 1;
                 template_idx += 1;
                 continue;
+            }
             if to_infer_part.is_marker() { to_infer_idx += 1; continue; }
             if template_part.is_marker() { template_idx += 1; continue; }
             // Types are not equal and not markers. So check if we can infer
             // anything
             if let Some(depth_change) = Self::infer_part_for_single_type(
                 to_infer, &mut to_infer_idx, template, &mut template_idx
             ) {
                 depth += depth_change;
                 modified = true;
                 continue;
+            }
             if !forced_template {
                 // We cannot infer anything, but the template may still be
                 // compatible with the type we're inferring
                 if let Some(depth_change) = Self::check_part_for_single_type(
                     template, &mut template_idx, &to_infer.parts, &mut to_infer_idx
                 ) {
                     depth += depth_change;
                     continue;
+                }
+            }
             return SingleInferenceResult::Incompatible
+        }
         if modified {
             to_infer.recompute_is_done();
             return SingleInferenceResult::Modified;
         } else {
             return SingleInferenceResult::Unmodified;
+        }
+    }
     /// Checks if both types are compatible, doesn't perform any inference
     fn check_subtrees(
         type_parts_a: &[InferenceTypePart], start_idx_a: usize,
         type_parts_b: &[InferenceTypePart], start_idx_b: usize
     ) -> bool {
         let mut depth = 1;
         let mut idx_a = start_idx_a;
         let mut idx_b = start_idx_b;
         while depth > 0 {
             let part_a = &type_parts_a[idx_a];
             let part_b = &type_parts_b[idx_b];
             if part_a == part_b {
                 let depth_change = part_a.depth_change();
                 depth += depth_change;
                 debug_assert_eq!(depth_change, part_b.depth_change());
                 idx_a += 1;
                 idx_b += 1;
                 continue;
+            }
             if part_a.is_marker() { idx_a += 1; continue; }
             if part_b.is_marker() { idx_b += 1; continue; }
             if let Some(depth_change) = Self::check_part_for_single_type(
                 type_parts_a, &mut idx_a, type_parts_b, &mut idx_b
             ) {
                 depth += depth_change;
                 continue;
+            }
             if let Some(depth_change) = Self::check_part_for_single_type(
                 type_parts_b, &mut idx_b, type_parts_a, &mut idx_a
             ) {
                 depth += depth_change;
                 continue;
+            }
             return false;
+        }
         true
+    }
     /// Performs the conversion of the inference type into a concrete type.
     /// By calling this function you must make sure that no unspecified types
     /// (e.g. Unknown or IntegerLike) exist in the type. Will not clear or check
     /// if the supplied `ConcreteType` is empty, will simply append to the parts
     /// vector.
     fn write_concrete_type(&self, concrete_type: &mut ConcreteType) {
         use InferenceTypePart as ITP;
         use ConcreteTypePart as CTP;
         // Make sure inference type is specified but concrete type is not yet specified
         debug_assert!(!self.parts.is_empty());
         concrete_type.parts.reserve(self.parts.len());
         let mut idx = 0;
         while idx < self.parts.len() {
             let part = &self.parts[idx];
             let converted_part = match part {
                 ITP::Marker(_) => {
                     // Markers are removed when writing to the concrete type.
                     idx += 1;
                     continue;
                 },
                 ITP::Unknown | ITP::NumberLike |
                 ITP::IntegerLike | ITP::ArrayLike | ITP::PortLike => {
                     // Should not happen if type inferencing works correctly: we
                     // should have returned a programmer-readable error or have
                     // inferred all types.
                     unreachable!("attempted to convert inference type part {:?} into concrete type", part);
                 },
                 ITP::Void => CTP::Void,
                 ITP::Message => CTP::Message,
                 ITP::Bool => CTP::Bool,
                 ITP::UInt8 => CTP::UInt8,
                 ITP::UInt16 => CTP::UInt16,
                 ITP::UInt32 => CTP::UInt32,
                 ITP::UInt64 => CTP::UInt64,
                 ITP::SInt8 => CTP::SInt8,
                 ITP::SInt16 => CTP::SInt16,
                 ITP::SInt32 => CTP::SInt32,
                 ITP::SInt64 => CTP::SInt64,
                 ITP::Character => CTP::Character,
                 ITP::String => {
                     // Inferred type has a 'char' subtype to simplify array
                     // checking, we remove it here.
                     debug_assert_eq!(self.parts[idx + 1], InferenceTypePart::Character);
                     idx += 1;
                     CTP::String
                 },
                 ITP::Array => CTP::Array,
                 ITP::Slice => CTP::Slice,
                 ITP::Input => CTP::Input,
                 ITP::Output => CTP::Output,
                 ITP::Tuple(num) => CTP::Tuple(*num),
                 ITP::Instance(id, num) => CTP::Instance(*id, *num),
             };
             concrete_type.parts.push(converted_part);
             idx += 1;
+        }
+    }
     /// Writes a human-readable version of the type to a string. This is used
     /// to display error messages
     fn write_display_name(
         buffer: &mut String, heap: &Heap, parts: &[InferenceTypePart], mut idx: usize
     ) -> usize {
         use InferenceTypePart as ITP;
         match &parts[idx] {
             ITP::Marker(_marker_idx) => {
                 if debug_log_enabled!() {
                     buffer.push_str(&format!("{{Marker:{}}}", *_marker_idx));
+                }
                 idx = Self::write_display_name(buffer, heap, parts, idx + 1);
             },
             ITP::Unknown => buffer.push_str("?"),
             ITP::NumberLike => buffer.push_str("numberlike"),
             ITP::IntegerLike => buffer.push_str("integerlike"),
             ITP::ArrayLike => {
                 idx = Self::write_display_name(buffer, heap, parts, idx + 1);
                 buffer.push_str("[?]");
             },
             ITP::PortLike => {
                 buffer.push_str("portlike<");
                 idx = Self::write_display_name(buffer, heap, parts, idx + 1);
                 buffer.push('>');
+            }
             ITP::Void => buffer.push_str("void"),
             ITP::Bool => buffer.push_str(KW_TYPE_BOOL_STR),
             ITP::UInt8 => buffer.push_str(KW_TYPE_UINT8_STR),
             ITP::UInt16 => buffer.push_str(KW_TYPE_UINT16_STR),
             ITP::UInt32 => buffer.push_str(KW_TYPE_UINT32_STR),
             ITP::UInt64 => buffer.push_str(KW_TYPE_UINT64_STR),
             ITP::SInt8 => buffer.push_str(KW_TYPE_SINT8_STR),
             ITP::SInt16 => buffer.push_str(KW_TYPE_SINT16_STR),
             ITP::SInt32 => buffer.push_str(KW_TYPE_SINT32_STR),
             ITP::SInt64 => buffer.push_str(KW_TYPE_SINT64_STR),
             ITP::Character => buffer.push_str(KW_TYPE_CHAR_STR),
             ITP::String => {
                 buffer.push_str(KW_TYPE_STRING_STR);
                 idx += 1; // skip the 'char' subtype
             },
             ITP::Message => {
                 buffer.push_str(KW_TYPE_MESSAGE_STR);
                 buffer.push('<');
                 idx = Self::write_display_name(buffer, heap, parts, idx + 1);
                 buffer.push('>');
             },
             ITP::Array => {
                 idx = Self::write_display_name(buffer, heap, parts, idx + 1);
                 buffer.push_str("[]");
             },
             ITP::Slice => {
                 idx = Self::write_display_name(buffer, heap, parts, idx + 1);
                 buffer.push_str("[..]");
             },
             ITP::Input => {
                 buffer.push_str(KW_TYPE_IN_PORT_STR);
                 buffer.push('<');
                 idx = Self::write_display_name(buffer, heap, parts, idx + 1);
                 buffer.push('>');
             },
             ITP::Output => {
                 buffer.push_str(KW_TYPE_OUT_PORT_STR);
                 buffer.push('<');
                 idx = Self::write_display_name(buffer, heap, parts, idx + 1);
                 buffer.push('>');
             },
             ITP::Tuple(num_sub) => {
                 buffer.push('(');
                 if *num_sub > 0 {
                     idx = Self::write_display_name(buffer, heap, parts, idx + 1);
                     for _sub_idx in 1..*num_sub {
                         buffer.push_str(", ");
                         idx = Self::write_display_name(buffer, heap, parts, idx + 1);
+                    }
+                }
                 buffer.push(')');
+            }
             ITP::Instance(definition_id, num_sub) => {
                 let definition = &heap[*definition_id];
                 buffer.push_str(definition.identifier().value.as_str());
                 if *num_sub > 0 {
                     buffer.push('<');
                     idx = Self::write_display_name(buffer, heap, parts, idx + 1);
                     for _sub_idx in 1..*num_sub {
                         buffer.push_str(", ");
                         idx = Self::write_display_name(buffer, heap, parts, idx + 1);
+                    }
                     buffer.push('>');
+                }
             },
+        }
         idx
+    }
     /// Returns the display name of a (part of) the type tree. Will allocate a
     /// string.
     fn partial_display_name(heap: &Heap, parts: &[InferenceTypePart]) -> String {
         let mut buffer = String::with_capacity(parts.len() * 6);
         Self::write_display_name(&mut buffer, heap, parts, 0);
         buffer
+    }
     /// Returns the display name of the full type tree. Will allocate a string.
     fn display_name(&self, heap: &Heap) -> String {
         Self::partial_display_name(heap, &self.parts)
+    }
+}
 impl Default for InferenceType {
     fn default() -> Self {
         Self{
             has_marker: false,
             is_done: false,
             parts: Vec::new(),
+        }
+    }
+}
 /// Iterator over the subtrees that follow a marker in an `InferenceType`
 /// instance. Returns immutable slices over the internal parts
 struct InferenceTypeMarkerIter<'a> {
     parts: &'a [InferenceTypePart],
     idx: usize,
+}
 impl<'a> InferenceTypeMarkerIter<'a> {
     fn new(parts: &'a [InferenceTypePart]) -> Self {
         Self{ parts, idx: 0 }
+    }
+}
 impl<'a> Iterator for InferenceTypeMarkerIter<'a> {
     type Item = (u32, &'a [InferenceTypePart]);
     fn next(&mut self) -> Option<Self::Item> {
         // Iterate until we find a marker
         while self.idx < self.parts.len() {
             if let InferenceTypePart::Marker(marker) = self.parts[self.idx] {
                 // Found a marker, find the subtree end
                 let start_idx = self.idx + 1;
                 let end_idx = InferenceType::find_subtree_end_idx(self.parts, start_idx);
                 // Modify internal index, then return items
                 self.idx = end_idx;
                 return Some((marker, &self.parts[start_idx..end_idx]));
+            }
             self.idx += 1;
+        }
         None
+    }
+}
 #[derive(Debug, PartialEq, Eq)]
 enum DualInferenceResult {
     Neither,        // neither argument is clarified
     First,          // first argument is clarified using the second one
     Second,         // second argument is clarified using the first one
     Both,           // both arguments are clarified
     Incompatible,   // types are incompatible: programmer error
+}
 impl DualInferenceResult {
     fn modified_lhs(&self) -> bool {
         match self {
             DualInferenceResult::First | DualInferenceResult::Both => true,
             _ => false
+        }
+    }
     fn modified_rhs(&self) -> bool {
         match self {
             DualInferenceResult::Second | DualInferenceResult::Both => true,
             _ => false
+        }
+    }
+}
 #[derive(Debug, PartialEq, Eq)]
 enum SingleInferenceResult {
     Unmodified,
     Modified,
     Incompatible
+}
 enum DefinitionType{
     Component(ComponentDefinitionId),
     Function(FunctionDefinitionId),
+}
 impl DefinitionType {
     fn definition_id(&self) -> DefinitionId {
         match self {
             DefinitionType::Component(v) => v.upcast(),
             DefinitionType::Function(v) => v.upcast(),
+        }
+    }
+}
 pub(crate) struct ResolveQueueElement {
     // Note that using the `definition_id` and the `monomorph_idx` one may
     // query the type table for the full procedure type, thereby retrieving
     // the polymorphic arguments to the procedure.
     pub(crate) root_id: RootId,
     pub(crate) definition_id: DefinitionId,
     pub(crate) reserved_monomorph_idx: i32,
+}
 pub(crate) type ResolveQueue = Vec<ResolveQueueElement>;
 #[derive(Clone)]
 struct InferenceExpression {
     expr_type: InferenceType,       // result type from expression
     expr_id: ExpressionId,          // expression that is evaluated
     field_or_monomorph_idx: i32,    // index of field, of index of monomorph array in type table
     extra_data_idx: i32,     // index of extra data needed for inference
+}
 impl Default for InferenceExpression {
     fn default() -> Self {
         Self{
             expr_type: InferenceType::default(),
             expr_id: ExpressionId::new_invalid(),
             field_or_monomorph_idx: -1,
             extra_data_idx: -1,
+        }
+    }
+}
 /// This particular visitor will recurse depth-first into the AST and ensures
 /// that all expressions have the appropriate types.
 pub(crate) struct PassTyping {
     // Current definition we're typechecking.
     reserved_idx: i32,
     definition_type: DefinitionType,
     poly_vars: Vec<ConcreteType>,
     // Buffers for iteration over substatements and subexpressions
     stmt_buffer: Vec<StatementId>,
     expr_buffer: Vec<ExpressionId>,
     // Mapping from parser type to inferred type. We attempt to continue to
     // specify these types until we're stuck or we've fully determined the type.
     var_types: HashMap<VariableId, VarData>,            // types of variables
     expr_types: Vec<InferenceExpression>,                     // will be transferred to type table at end
     extra_data: Vec<ExtraData>,       // data for polymorph inference
     // Keeping track of which expressions need to be reinferred because the
     // expressions they're linked to made progression on an associated type
     expr_queued: DequeSet<i32>,
+}
 // TODO: @Rename, this is used for a lot of type inferencing. It seems like
 //  there is a different underlying architecture waiting to surface.
 struct ExtraData {
     expr_id: ExpressionId, // the expression with which this data is associated
     definition_id: DefinitionId, // the definition, only used for user feedback
     /// Progression of polymorphic variables (if any)
     poly_vars: Vec<InferenceType>,
     /// Progression of types of call arguments or struct members
     embedded: Vec<InferenceType>,
     returned: InferenceType,
+}
 impl Default for ExtraData {
     fn default() -> Self {
         Self{
             expr_id: ExpressionId::new_invalid(),
             definition_id: DefinitionId::new_invalid(),
             poly_vars: Vec::new(),
             embedded: Vec::new(),
             returned: InferenceType::default(),
+        }
+    }
+}
 struct VarData {
     /// Type of the variable
     var_type: InferenceType,
     /// VariableExpressions that use the variable
     used_at: Vec<ExpressionId>,
     /// For channel statements we link to the other variable such that when one
     /// channel's interior type is resolved, we can also resolve the other one.
     linked_var: Option<VariableId>,
+}
 impl VarData {
     fn new_channel(var_type: InferenceType, other_port: VariableId) -> Self {
         Self{ var_type, used_at: Vec::new(), linked_var: Some(other_port) }
+    }
     fn new_local(var_type: InferenceType) -> Self {
         Self{ var_type, used_at: Vec::new(), linked_var: None }
+    }
+}
 impl PassTyping {
     pub(crate) fn new() -> Self {
         PassTyping {
             reserved_idx: -1,
             definition_type: DefinitionType::Function(FunctionDefinitionId::new_invalid()),
             poly_vars: Vec::new(),
             stmt_buffer: Vec::with_capacity(STMT_BUFFER_INIT_CAPACITY),
             expr_buffer: Vec::with_capacity(EXPR_BUFFER_INIT_CAPACITY),
             var_types: HashMap::new(),
             expr_types: Vec::new(),
             extra_data: Vec::new(),
             expr_queued: DequeSet::new(),
+        }
+    }
     pub(crate) fn queue_module_definitions(ctx: &mut Ctx, queue: &mut ResolveQueue) {
         debug_assert_eq!(ctx.module().phase, ModuleCompilationPhase::ValidatedAndLinked);
         let root_id = ctx.module().root_id;
         let root = &ctx.heap.protocol_descriptions[root_id];
         for definition_id in &root.definitions {
             let definition = &ctx.heap[*definition_id];
             let first_concrete_part = match definition {
                 Definition::Function(definition) => {
                     if definition.poly_vars.is_empty() {
                         Some(ConcreteTypePart::Function(*definition_id, 0))
                     } else {
                         None
+                    }
+                }
                 Definition::Component(definition) => {
                     if definition.poly_vars.is_empty() {
                         Some(ConcreteTypePart::Component(*definition_id, 0))
                     } else {
                         None
+                    }
                 },
                 Definition::Enum(_) | Definition::Struct(_) | Definition::Union(_) => None,
             };
             if let Some(first_concrete_part) = first_concrete_part {
                 let concrete_type = ConcreteType{ parts: vec![first_concrete_part] };
                 let reserved_idx = ctx.types.reserve_procedure_monomorph_index(definition_id, concrete_type);
                 queue.push(ResolveQueueElement{
                     root_id,
                     definition_id: *definition_id,
                     reserved_monomorph_idx: reserved_idx,
                 })
+            }
+        }
+    }
     pub(crate) fn handle_module_definition(
         &mut self, ctx: &mut Ctx, queue: &mut ResolveQueue, element: ResolveQueueElement
     ) -> VisitorResult {
         self.reset();
         debug_assert_eq!(ctx.module().root_id, element.root_id);
         debug_assert!(self.poly_vars.is_empty());
         // Prepare for visiting the definition
         self.reserved_idx = element.reserved_monomorph_idx;
         let proc_base = ctx.types.get_base_definition(&element.definition_id).unwrap();
         if proc_base.is_polymorph {
             let proc_monos = proc_base.definition.procedure_monomorphs();
             let proc_mono = &(*proc_monos)[element.reserved_monomorph_idx as usize];
             for poly_arg in proc_mono.concrete_type.embedded_iter(0) {
             let monomorph = ctx.types.get_monomorph(element.reserved_monomorph_idx);
             for poly_arg in monomorph.concrete_type.embedded_iter(0) {
                 self.poly_vars.push(ConcreteType{ parts: Vec::from(poly_arg) });
+            }
+        }
         // Visit the definition, setting up the type resolving process, then
         // (attempt to) resolve all types
         self.visit_definition(ctx, element.definition_id)?;
         self.resolve_types(ctx, queue)?;
         Ok(())
+    }
     fn reset(&mut self) {
         self.reserved_idx = -1;
         self.definition_type = DefinitionType::Function(FunctionDefinitionId::new_invalid());
         self.poly_vars.clear();
         self.stmt_buffer.clear();
         self.expr_buffer.clear();
         self.var_types.clear();
         self.expr_types.clear();
         self.extra_data.clear();
         self.expr_queued.clear();
+    }
+}
 impl Visitor for PassTyping {
     // Definitions
     fn visit_component_definition(&mut self, ctx: &mut Ctx, id: ComponentDefinitionId) -> VisitorResult {
         self.definition_type = DefinitionType::Component(id);
         let comp_def = &ctx.heap[id];
         debug_assert_eq!(comp_def.poly_vars.len(), self.poly_vars.len(), "component polyvars do not match imposed polyvars");
         debug_log!("{}", "-".repeat(50));
         debug_log!("Visiting component '{}': {}", comp_def.identifier.value.as_str(), id.0.index);
         debug_log!("{}", "-".repeat(50));
         // Reserve data for expression types
         debug_assert!(self.expr_types.is_empty());
         self.expr_types.resize(comp_def.num_expressions_in_body as usize, Default::default());
         // Visit parameters
         for param_id in comp_def.parameters.clone() {
             let param = &ctx.heap[param_id];
             let var_type = self.determine_inference_type_from_parser_type_elements(&param.parser_type.elements, true);
             debug_assert!(var_type.is_done, "expected component arguments to be concrete types");
             self.var_types.insert(param_id, VarData::new_local(var_type));
+        }
         // Visit the body and all of its expressions
         let body_stmt_id = ctx.heap[id].body;
         self.visit_block_stmt(ctx, body_stmt_id)
+    }
     fn visit_function_definition(&mut self, ctx: &mut Ctx, id: FunctionDefinitionId) -> VisitorResult {
         self.definition_type = DefinitionType::Function(id);
         let func_def = &ctx.heap[id];
         debug_assert_eq!(func_def.poly_vars.len(), self.poly_vars.len(), "function polyvars do not match imposed polyvars");
         debug_log!("{}", "-".repeat(50));
         debug_log!("Visiting function '{}': {}", func_def.identifier.value.as_str(), id.0.index);
         if debug_log_enabled!() {
             debug_log!("Polymorphic variables:");
             for (_idx, poly_var) in self.poly_vars.iter().enumerate() {
                 let mut infer_type_parts = Vec::new();
                 Self::determine_inference_type_from_concrete_type(
                     &mut infer_type_parts, &poly_var.parts
                 );
                 let _infer_type = InferenceType::new(false, true, infer_type_parts);
                 debug_log!(" - [{:03}] {:?}", _idx, _infer_type.display_name(&ctx.heap));
+            }
+        }
         debug_log!("{}", "-".repeat(50));
         // Reserve data for expression types
         debug_assert!(self.expr_types.is_empty());
         self.expr_types.resize(func_def.num_expressions_in_body as usize, Default::default());
         // Visit parameters
         for param_id in func_def.parameters.clone() {
             let param = &ctx.heap[param_id];
             let var_type = self.determine_inference_type_from_parser_type_elements(&param.parser_type.elements, true);
             debug_assert!(var_type.is_done, "expected function arguments to be concrete types");
             self.var_types.insert(param_id, VarData::new_local(var_type));
+        }
         // Visit all of the expressions within the body
         let body_stmt_id = ctx.heap[id].body;
         self.visit_block_stmt(ctx, body_stmt_id)
+    }
     // Statements
     fn visit_block_stmt(&mut self, ctx: &mut Ctx, id: BlockStatementId) -> VisitorResult {
         // Transfer statements for traversal
         let block = &ctx.heap[id];
         for stmt_id in block.statements.clone() {
             self.visit_stmt(ctx, stmt_id)?;
+        }
         Ok(())
+    }
     fn visit_local_memory_stmt(&mut self, ctx: &mut Ctx, id: MemoryStatementId) -> VisitorResult {
         let memory_stmt = &ctx.heap[id];
         let local = &ctx.heap[memory_stmt.variable];
         let var_type = self.determine_inference_type_from_parser_type_elements(&local.parser_type.elements, true);
         self.var_types.insert(memory_stmt.variable, VarData::new_local(var_type));
         Ok(())
+    }
     fn visit_local_channel_stmt(&mut self, ctx: &mut Ctx, id: ChannelStatementId) -> VisitorResult {
         let channel_stmt = &ctx.heap[id];
         let from_local = &ctx.heap[channel_stmt.from];
         let from_var_type = self.determine_inference_type_from_parser_type_elements(&from_local.parser_type.elements, true);
         self.var_types.insert(from_local.this, VarData::new_channel(from_var_type, channel_stmt.to));
         let to_local = &ctx.heap[channel_stmt.to];
         let to_var_type = self.determine_inference_type_from_parser_type_elements(&to_local.parser_type.elements, true);
         self.var_types.insert(to_local.this, VarData::new_channel(to_var_type, channel_stmt.from));
         Ok(())
+    }
     fn visit_labeled_stmt(&mut self, ctx: &mut Ctx, id: LabeledStatementId) -> VisitorResult {
         let labeled_stmt = &ctx.heap[id];
         let substmt_id = labeled_stmt.body;
         self.visit_stmt(ctx, substmt_id)
+    }
     fn visit_if_stmt(&mut self, ctx: &mut Ctx, id: IfStatementId) -> VisitorResult {
         let if_stmt = &ctx.heap[id];
         let true_body_id = if_stmt.true_body;
         let false_body_id = if_stmt.false_body;
         let test_expr_id = if_stmt.test;
         self.visit_expr(ctx, test_expr_id)?;
         self.visit_block_stmt(ctx, true_body_id)?;
         if let Some(false_body_id) = false_body_id {
             self.visit_block_stmt(ctx, false_body_id)?;
+        }
         Ok(())
+    }
     fn visit_while_stmt(&mut self, ctx: &mut Ctx, id: WhileStatementId) -> VisitorResult {
         let while_stmt = &ctx.heap[id];
         let body_id = while_stmt.body;
         let test_expr_id = while_stmt.test;
         self.visit_expr(ctx, test_expr_id)?;
         self.visit_block_stmt(ctx, body_id)?;
         Ok(())
+    }
     fn visit_synchronous_stmt(&mut self, ctx: &mut Ctx, id: SynchronousStatementId) -> VisitorResult {
         let sync_stmt = &ctx.heap[id];
         let body_id = sync_stmt.body;
         self.visit_block_stmt(ctx, body_id)
+    }
     fn visit_fork_stmt(&mut self, ctx: &mut Ctx, id: ForkStatementId) -> VisitorResult {
         let fork_stmt = &ctx.heap[id];
         let left_body_id = fork_stmt.left_body;
         let right_body_id = fork_stmt.right_body;
         self.visit_block_stmt(ctx, left_body_id)?;
         if let Some(right_body_id) = right_body_id {
             self.visit_block_stmt(ctx, right_body_id)?;
+        }
         Ok(())
+    }
     fn visit_return_stmt(&mut self, ctx: &mut Ctx, id: ReturnStatementId) -> VisitorResult {
         let return_stmt = &ctx.heap[id];
         debug_assert_eq!(return_stmt.expressions.len(), 1);
         let expr_id = return_stmt.expressions[0];
         self.visit_expr(ctx, expr_id)
+    }
     fn visit_new_stmt(&mut self, ctx: &mut Ctx, id: NewStatementId) -> VisitorResult {
         let new_stmt = &ctx.heap[id];
         let call_expr_id = new_stmt.expression;
         self.visit_call_expr(ctx, call_expr_id)
+    }
     fn visit_expr_stmt(&mut self, ctx: &mut Ctx, id: ExpressionStatementId) -> VisitorResult {
         let expr_stmt = &ctx.heap[id];
         let subexpr_id = expr_stmt.expression;
         self.visit_expr(ctx, subexpr_id)
+    }
     // Expressions
     fn visit_assignment_expr(&mut self, ctx: &mut Ctx, id: AssignmentExpressionId) -> VisitorResult {
         let upcast_id = id.upcast();
         self.insert_initial_expr_inference_type(ctx, upcast_id)?;
         let assign_expr = &ctx.heap[id];
         let left_expr_id = assign_expr.left;
         let right_expr_id = assign_expr.right;
         self.visit_expr(ctx, left_expr_id)?;
         self.visit_expr(ctx, right_expr_id)?;
         self.progress_assignment_expr(ctx, id)
+    }
     fn visit_binding_expr(&mut self, ctx: &mut Ctx, id: BindingExpressionId) -> VisitorResult {
         let upcast_id = id.upcast();
         self.insert_initial_expr_inference_type(ctx, upcast_id)?;
         let binding_expr = &ctx.heap[id];
         let bound_to_id = binding_expr.bound_to;
         let bound_from_id = binding_expr.bound_from;
         self.visit_expr(ctx, bound_to_id)?;
         self.visit_expr(ctx, bound_from_id)?;
         self.progress_binding_expr(ctx, id)
+    }
     fn visit_conditional_expr(&mut self, ctx: &mut Ctx, id: ConditionalExpressionId) -> VisitorResult {
         let upcast_id = id.upcast();
         self.insert_initial_expr_inference_type(ctx, upcast_id)?;
         let conditional_expr = &ctx.heap[id];
         let test_expr_id = conditional_expr.test;
         let true_expr_id = conditional_expr.true_expression;
         let false_expr_id = conditional_expr.false_expression;
         self.visit_expr(ctx, test_expr_id)?;
         self.visit_expr(ctx, true_expr_id)?;
         self.visit_expr(ctx, false_expr_id)?;
         self.progress_conditional_expr(ctx, id)
+    }
     fn visit_binary_expr(&mut self, ctx: &mut Ctx, id: BinaryExpressionId) -> VisitorResult {
         let upcast_id = id.upcast();
         self.insert_initial_expr_inference_type(ctx, upcast_id)?;
         let binary_expr = &ctx.heap[id];
         let lhs_expr_id = binary_expr.left;
         let rhs_expr_id = binary_expr.right;
         self.visit_expr(ctx, lhs_expr_id)?;
         self.visit_expr(ctx, rhs_expr_id)?;
         self.progress_binary_expr(ctx, id)
+    }
     fn visit_unary_expr(&mut self, ctx: &mut Ctx, id: UnaryExpressionId) -> VisitorResult {
         let upcast_id = id.upcast();
         self.insert_initial_expr_inference_type(ctx, upcast_id)?;
         let unary_expr = &ctx.heap[id];
         let arg_expr_id = unary_expr.expression;
         self.visit_expr(ctx, arg_expr_id)?;
         self.progress_unary_expr(ctx, id)
+    }
     fn visit_indexing_expr(&mut self, ctx: &mut Ctx, id: IndexingExpressionId) -> VisitorResult {
         let upcast_id = id.upcast();
         self.insert_initial_expr_inference_type(ctx, upcast_id)?;
         let indexing_expr = &ctx.heap[id];
         let subject_expr_id = indexing_expr.subject;
         let index_expr_id = indexing_expr.index;
         self.visit_expr(ctx, subject_expr_id)?;
         self.visit_expr(ctx, index_expr_id)?;
         self.progress_indexing_expr(ctx, id)
+    }
     fn visit_slicing_expr(&mut self, ctx: &mut Ctx, id: SlicingExpressionId) -> VisitorResult {
         let upcast_id = id.upcast();
         self.insert_initial_expr_inference_type(ctx, upcast_id)?;
         let slicing_expr = &ctx.heap[id];
         let subject_expr_id = slicing_expr.subject;
         let from_expr_id = slicing_expr.from_index;
         let to_expr_id = slicing_expr.to_index;
         self.visit_expr(ctx, subject_expr_id)?;
         self.visit_expr(ctx, from_expr_id)?;
         self.visit_expr(ctx, to_expr_id)?;
         self.progress_slicing_expr(ctx, id)
+    }
     fn visit_select_expr(&mut self, ctx: &mut Ctx, id: SelectExpressionId) -> VisitorResult {
         let upcast_id = id.upcast();
         self.insert_initial_expr_inference_type(ctx, upcast_id)?;
         let select_expr = &ctx.heap[id];
         let subject_expr_id = select_expr.subject;
         self.visit_expr(ctx, subject_expr_id)?;
         self.progress_select_expr(ctx, id)
+    }
     fn visit_literal_expr(&mut self, ctx: &mut Ctx, id: LiteralExpressionId) -> VisitorResult {
         let upcast_id = id.upcast();
         self.insert_initial_expr_inference_type(ctx, upcast_id)?;
         let literal_expr = &ctx.heap[id];
         match &literal_expr.value {
             Literal::Null | Literal::False | Literal::True |
             Literal::Integer(_) | Literal::Character(_) | Literal::String(_) => {
                 // No subexpressions
             },
             Literal::Struct(literal) => {
                 // TODO: @performance
                 let expr_ids: Vec<_> = literal.fields
                     .iter()
                     .map(|f| f.value)
                     .collect();
                 self.insert_initial_struct_polymorph_data(ctx, id);
                 for expr_id in expr_ids {
                     self.visit_expr(ctx, expr_id)?;
+                }
             },
             Literal::Enum(_) => {
                 // Enumerations do not carry any subexpressions, but may still
                 // have a user-defined polymorphic marker variable. For this
                 // reason we may still have to apply inference to this
                 // polymorphic variable
                 self.insert_initial_enum_polymorph_data(ctx, id);
             },
             Literal::Union(literal) => {
                 // May carry subexpressions and polymorphic arguments
                 // TODO: @performance
                 let expr_ids = literal.values.clone();
                 self.insert_initial_union_polymorph_data(ctx, id);
                 for expr_id in expr_ids {
                     self.visit_expr(ctx, expr_id)?;
+                }
             },
             Literal::Array(expressions) => {
                 // TODO: @performance
                 let expr_ids = expressions.clone();
                 for expr_id in expr_ids {
                     self.visit_expr(ctx, expr_id)?;
+                }
+            }
+        }
         self.progress_literal_expr(ctx, id)
+    }
     fn visit_cast_expr(&mut self, ctx: &mut Ctx, id: CastExpressionId) -> VisitorResult {
         let upcast_id = id.upcast();
         self.insert_initial_expr_inference_type(ctx, upcast_id)?;
         let cast_expr = &ctx.heap[id];
         let subject_expr_id = cast_expr.subject;
         self.visit_expr(ctx, subject_expr_id)?;
         self.progress_cast_expr(ctx, id)
+    }
     fn visit_call_expr(&mut self, ctx: &mut Ctx, id: CallExpressionId) -> VisitorResult {
         let upcast_id = id.upcast();
         self.insert_initial_expr_inference_type(ctx, upcast_id)?;
         self.insert_initial_call_polymorph_data(ctx, id);
         // By default we set the polymorph idx for calls to 0. If the call ends
         // up not being a polymorphic one, then we will select the default
         // expression types in the type table
         let call_expr = &ctx.heap[id];
         self.expr_types[call_expr.unique_id_in_definition as usize].field_or_monomorph_idx = 0;
         // Visit all arguments
         for arg_expr_id in call_expr.arguments.clone() { // TODO: @Performance
             self.visit_expr(ctx, arg_expr_id)?;
+        }
         self.progress_call_expr(ctx, id)
+    }
     fn visit_variable_expr(&mut self, ctx: &mut Ctx, id: VariableExpressionId) -> VisitorResult {
         let upcast_id = id.upcast();
         self.insert_initial_expr_inference_type(ctx, upcast_id)?;
         let var_expr = &ctx.heap[id];
         debug_assert!(var_expr.declaration.is_some());
         // Not pretty: if a binding expression, then this is the first time we
         // encounter the variable, so we still need to insert the variable data.
         let declaration = &ctx.heap[var_expr.declaration.unwrap()];
         if !self.var_types.contains_key(&declaration.this)  {
             debug_assert!(declaration.kind == VariableKind::Binding);
             let var_type = self.determine_inference_type_from_parser_type_elements(
                 &declaration.parser_type.elements, true
             );
             self.var_types.insert(declaration.this, VarData{
                 var_type,
                 used_at: vec![upcast_id],
                 linked_var: None
             });
         } else {
             let var_data = self.var_types.get_mut(&declaration.this).unwrap();
             var_data.used_at.push(upcast_id);
+        }
         self.progress_variable_expr(ctx, id)
+    }
+}
 impl PassTyping {
     #[allow(dead_code)] // used when debug flag at the top of this file is true.
     fn debug_get_display_name(&self, ctx: &Ctx, expr_id: ExpressionId) -> String {
         let expr_idx = ctx.heap[expr_id].get_unique_id_in_definition();
         let expr_type = &self.expr_types[expr_idx as usize].expr_type;
         expr_type.display_name(&ctx.heap)
+    }
     fn resolve_types(&mut self, ctx: &mut Ctx, queue: &mut ResolveQueue) -> Result<(), ParseError> {
         // Keep inferring until we can no longer make any progress
         while !self.expr_queued.is_empty() {
             let next_expr_idx = self.expr_queued.pop_front().unwrap();
             self.progress_expr(ctx, next_expr_idx)?;
+        }
         // Helper for transferring polymorphic variables to concrete types and
         // checking if they're completely specified
         fn inference_type_to_concrete_type(
             ctx: &Ctx, expr_id: ExpressionId, inference: &Vec<InferenceType>,
             first_concrete_part: ConcreteTypePart,
         ) -> Result<ConcreteType, ParseError> {
             // Prepare storage vector
             let mut num_inference_parts = 0;
             for inference_type in inference {
                 num_inference_parts += inference_type.parts.len();
+            }
             let mut concrete_type = ConcreteType{
                 parts: Vec::with_capacity(1 + num_inference_parts),
             };
             concrete_type.parts.push(first_concrete_part);
             // Go through all polymorphic arguments and add them to the concrete
             // types.
             for (poly_idx, poly_type) in inference.iter().enumerate() {
                 if !poly_type.is_done {
                     let expr = &ctx.heap[expr_id];
                     let definition = match expr {
                         Expression::Call(expr) => expr.definition,
                         Expression::Literal(expr) => match &expr.value {
                             Literal::Enum(lit) => lit.definition,
                             Literal::Union(lit) => lit.definition,
                             Literal::Struct(lit) => lit.definition,
                             _ => unreachable!()
                         },
                         _ => unreachable!(),
                     };
                     let poly_vars = ctx.heap[definition].poly_vars();
                     return Err(ParseError::new_error_at_span(
                         &ctx.module().source, expr.operation_span(), format!(
                             "could not fully infer the type of polymorphic variable '{}' of this expression (got '{}')",
                             poly_vars[poly_idx].value.as_str(), poly_type.display_name(&ctx.heap)
+                        )
                     ));
+                }
                 poly_type.write_concrete_type(&mut concrete_type);
+            }
             Ok(concrete_type)
+        }
         // Inference is now done. But we may still have uninferred types. So we
         // check for these.
         for (infer_expr_idx, infer_expr) in self.expr_types.iter_mut().enumerate() {
             let expr_type = &mut infer_expr.expr_type;
             if !expr_type.is_done {
                 // Auto-infer numberlike/integerlike types to a regular int
                 if expr_type.parts.len() == 1 && expr_type.parts[0] == InferenceTypePart::IntegerLike {
                     expr_type.parts[0] = InferenceTypePart::SInt32;
                     self.expr_queued.push_back(infer_expr_idx as i32);
                 } else {
                     let expr = &ctx.heap[infer_expr.expr_id];
                     return Err(ParseError::new_error_at_span(
                         &ctx.module().source, expr.full_span(), format!(
                             "could not fully infer the type of this expression (got '{}')",
                             expr_type.display_name(&ctx.heap)
+                        )
                     ));
+                }
+            }
             // Expression is fine, check if any extra data is attached
             if infer_expr.extra_data_idx < 0 { continue; }
             // Extra data is attached, perform typechecking and transfer
             // resolved information to the expression
             let extra_data = &self.extra_data[infer_expr.extra_data_idx as usize];
             if extra_data.poly_vars.is_empty() { continue; }
             // Note that only call and literal expressions need full inference.
             // Select expressions also use `extra_data`, but only for temporary
             // storage of the struct type whose field it is selecting.
             match &ctx.heap[extra_data.expr_id] {
                 Expression::Call(expr) => {
                     // Check if it is not a builtin function. If not, then
                     // construct the first part of the concrete type.
                     let first_concrete_part = if expr.method == Method::UserFunction {
                         ConcreteTypePart::Function(expr.definition, extra_data.poly_vars.len() as u32)
                     } else if expr.method == Method::UserComponent {
                         ConcreteTypePart::Component(expr.definition, extra_data.poly_vars.len() as u32)
                     } else {
                         // Builtin function
                         continue;
                     };
                     let definition_id = expr.definition;
                     let concrete_type = inference_type_to_concrete_type(
                         ctx, extra_data.expr_id, &extra_data.poly_vars, first_concrete_part
                     )?;
                     match ctx.types.get_procedure_monomorph_index(&definition_id, &concrete_type) {
+                    match ctx.types.get_procedure_monomorph_index(&definition_id, &concrete_type.parts) {
                         Some(reserved_idx) => {
                             // Already typechecked, or already put into the resolve queue
                             infer_expr.field_or_monomorph_idx = reserved_idx;
                         },
                         None => {
                             // Not typechecked yet, so add an entry in the queue
                             let reserved_idx = ctx.types.reserve_procedure_monomorph_index(&definition_id, concrete_type);
                             infer_expr.field_or_monomorph_idx = reserved_idx;
                             queue.push(ResolveQueueElement{
                                 root_id: ctx.heap[definition_id].defined_in(),
                                 definition_id,
                                 reserved_monomorph_idx: reserved_idx,
                             });
+                        }
+                    }
                 },
                 Expression::Literal(expr) => {
                     let definition_id = match &expr.value {
                         Literal::Enum(lit) => lit.definition,
                         Literal::Union(lit) => lit.definition,
                         Literal::Struct(lit) => lit.definition,
                         _ => unreachable!(),
                     };
                     let first_concrete_part = ConcreteTypePart::Instance(definition_id, extra_data.poly_vars.len() as u32);
                     let concrete_type = inference_type_to_concrete_type(
                         ctx, extra_data.expr_id, &extra_data.poly_vars, first_concrete_part
                     )?;
                     let mono_index = ctx.types.add_data_monomorph(ctx.modules, ctx.heap, ctx.arch, definition_id, concrete_type)?;
                     infer_expr.field_or_monomorph_idx = mono_index;
                 },
                 Expression::Select(_) => {
                     debug_assert!(infer_expr.field_or_monomorph_idx >= 0);
                 },
                 _ => {
                     unreachable!("handling extra data for expression {:?}", &ctx.heap[extra_data.expr_id]);
+                }
+            }
+        }
         // If we did any implicit type forcing, then our queue isn't empty
         // anymore
         while !self.expr_queued.is_empty() {
             let expr_idx = self.expr_queued.pop_back().unwrap();
             self.progress_expr(ctx, expr_idx)?;
+        }
         // Every expression checked, and new monomorphs are queued. Transfer the
         // expression information to the type table.
-        let (definition_id, procedure_arguments) = match &self.definition_type {
         let procedure_arguments = match &self.definition_type {
             DefinitionType::Component(id) => {
                 let definition = &ctx.heap[*id];
-                (id.upcast(), &definition.parameters)
                 &definition.parameters
             },
             DefinitionType::Function(id) => {
                 let definition = &ctx.heap[*id];
-                (id.upcast(), &definition.parameters)
                 &definition.parameters
             },
         };
-        let target = ctx.types.get_procedure_expression_data_mut(&definition_id, self.reserved_idx);
+        let target = ctx.types.get_procedure_monomorph_mut(self.reserved_idx);
         debug_assert!(target.arg_types.is_empty()); // makes sure we never queue a procedure's type inferencing twice
         debug_assert!(target.expr_data.is_empty());
         // - Write the arguments to the procedure
         target.arg_types.reserve(procedure_arguments.len());
         for argument_id in procedure_arguments {
             let mut concrete = ConcreteType::default();
             let argument_type = self.var_types.get(argument_id).unwrap();
             argument_type.var_type.write_concrete_type(&mut concrete);
             target.arg_types.push(concrete);
+        }
         // - Write the expression data
         target.expr_data.reserve(self.expr_types.len());
         for infer_expr in self.expr_types.iter() {
             let mut concrete = ConcreteType::default();
             infer_expr.expr_type.write_concrete_type(&mut concrete);
             target.expr_data.push(MonomorphExpression{
                 expr_type: concrete,
                 field_or_monomorph_idx: infer_expr.field_or_monomorph_idx
             });
+        }
         Ok(())
+    }
     fn progress_expr(&mut self, ctx: &mut Ctx, idx: i32) -> Result<(), ParseError> {
         let id = self.expr_types[idx as usize].expr_id; // TODO: @Temp
         match &ctx.heap[id] {
             Expression::Assignment(expr) => {
                 let id = expr.this;
                 self.progress_assignment_expr(ctx, id)
             },
             Expression::Binding(expr) => {
                 let id = expr.this;
                 self.progress_binding_expr(ctx, id)
             },
             Expression::Conditional(expr) => {
                 let id = expr.this;
                 self.progress_conditional_expr(ctx, id)
             },
             Expression::Binary(expr) => {
                 let id = expr.this;
                 self.progress_binary_expr(ctx, id)
             },
             Expression::Unary(expr) => {
                 let id = expr.this;
                 self.progress_unary_expr(ctx, id)
             },
             Expression::Indexing(expr) => {
                 let id = expr.this;
                 self.progress_indexing_expr(ctx, id)
             },
             Expression::Slicing(expr) => {
                 let id = expr.this;
                 self.progress_slicing_expr(ctx, id)
             },
             Expression::Select(expr) => {
                 let id = expr.this;
                 self.progress_select_expr(ctx, id)
             },
             Expression::Literal(expr) => {
                 let id = expr.this;
                 self.progress_literal_expr(ctx, id)
             },
             Expression::Cast(expr) => {
                 let id = expr.this;
                 self.progress_cast_expr(ctx, id)
             },
             Expression::Call(expr) => {
                 let id = expr.this;
                 self.progress_call_expr(ctx, id)
             },
             Expression::Variable(expr) => {
                 let id = expr.this;
                 self.progress_variable_expr(ctx, id)
+            }
+        }
+    }
     fn progress_assignment_expr(&mut self, ctx: &mut Ctx, id: AssignmentExpressionId) -> Result<(), ParseError> {
         use AssignmentOperator as AO;
         let upcast_id = id.upcast();
         let expr = &ctx.heap[id];
         let arg1_expr_id = expr.left;
         let arg2_expr_id = expr.right;
         debug_log!("Assignment expr '{:?}': {}", expr.operation, upcast_id.index);
         debug_log!(" * Before:");
         debug_log!("   - Arg1 type: {}", self.debug_get_display_name(ctx, arg1_expr_id));
         debug_log!("   - Arg2 type: {}", self.debug_get_display_name(ctx, arg2_expr_id));
         debug_log!("   - Expr type: {}", self.debug_get_display_name(ctx, upcast_id));
         // Assignment does not return anything (it operates like a statement)
         let progress_expr = self.apply_forced_constraint(ctx, upcast_id, &VOID_TEMPLATE)?;
         // Apply forced constraint to LHS value
         let progress_forced = match expr.operation {
             AO::Set =>
                 false,
             AO::Concatenated =>
                 self.apply_template_constraint(ctx, arg1_expr_id, &ARRAYLIKE_TEMPLATE)?,
             AO::Multiplied | AO::Divided | AO::Added | AO::Subtracted =>
                 self.apply_template_constraint(ctx, arg1_expr_id, &NUMBERLIKE_TEMPLATE)?,
             AO::Remained | AO::ShiftedLeft | AO::ShiftedRight |
             AO::BitwiseAnded | AO::BitwiseXored | AO::BitwiseOred =>
                 self.apply_template_constraint(ctx, arg1_expr_id, &INTEGERLIKE_TEMPLATE)?,
         };
         let (progress_arg1, progress_arg2) = self.apply_equal2_constraint(
             ctx, upcast_id, arg1_expr_id, 0, arg2_expr_id, 0
         )?;
         debug_log!(" * After:");
         debug_log!("   - Arg1 type [{}]: {}", progress_forced || progress_arg1, self.debug_get_display_name(ctx, arg1_expr_id));
         debug_log!("   - Arg2 type [{}]: {}", progress_arg2, self.debug_get_display_name(ctx, arg2_expr_id));
         debug_log!("   - Expr type [{}]: {}", progress_expr, self.debug_get_display_name(ctx, upcast_id));
         if progress_expr { self.queue_expr_parent(ctx, upcast_id); }
         if progress_forced || progress_arg1 { self.queue_expr(ctx, arg1_expr_id); }
         if progress_arg2 { self.queue_expr(ctx, arg2_expr_id); }
         Ok(())
+    }
     fn progress_binding_expr(&mut self, ctx: &mut Ctx, id: BindingExpressionId) -> Result<(), ParseError> {
         let upcast_id = id.upcast();
         let binding_expr = &ctx.heap[id];
         let bound_from_id = binding_expr.bound_from;
         let bound_to_id = binding_expr.bound_to;
         // Output is always a boolean. The two arguments should be of equal
         // type.
         let progress_expr = self.apply_forced_constraint(ctx, upcast_id, &BOOL_TEMPLATE)?;
         let (progress_from, progress_to) = self.apply_equal2_constraint(ctx, upcast_id, bound_from_id, 0, bound_to_id, 0)?;
         if progress_expr { self.queue_expr_parent(ctx, upcast_id); }
         if progress_from { self.queue_expr(ctx, bound_from_id); }
         if progress_to { self.queue_expr(ctx, bound_to_id); }
         Ok(())
+    }
     fn progress_conditional_expr(&mut self, ctx: &mut Ctx, id: ConditionalExpressionId) -> Result<(), ParseError> {
         // Note: test expression type is already enforced
         let upcast_id = id.upcast();
         let expr = &ctx.heap[id];
         let arg1_expr_id = expr.true_expression;
         let arg2_expr_id = expr.false_expression;
         debug_log!("Conditional expr: {}", upcast_id.index);
         debug_log!(" * Before:");
         debug_log!("   - Arg1 type: {}", self.debug_get_display_name(ctx, arg1_expr_id));
         debug_log!("   - Arg2 type: {}", self.debug_get_display_name(ctx, arg2_expr_id));
         debug_log!("   - Expr type: {}", self.debug_get_display_name(ctx, upcast_id));
         // I keep confusing myself: this applies equality of types between the
         // condition branches' types, and the result from the conditional
         // expression, because the result from the conditional is one of the
         // branches.
         let (progress_expr, progress_arg1, progress_arg2) = self.apply_equal3_constraint(
             ctx, upcast_id, arg1_expr_id, arg2_expr_id, 0
         )?;
         debug_log!(" * After:");
         debug_log!("   - Arg1 type [{}]: {}", progress_arg1, self.debug_get_display_name(ctx, arg1_expr_id));
         debug_log!("   - Arg2 type [{}]: {}", progress_arg2, self.debug_get_display_name(ctx, arg2_expr_id));
         debug_log!("   - Expr type [{}]: {}", progress_expr, self.debug_get_display_name(ctx, upcast_id));
         if progress_expr { self.queue_expr_parent(ctx, upcast_id); }
         if progress_arg1 { self.queue_expr(ctx, arg1_expr_id); }
         if progress_arg2 { self.queue_expr(ctx, arg2_expr_id); }
         Ok(())
+    }
     fn progress_binary_expr(&mut self, ctx: &mut Ctx, id: BinaryExpressionId) -> Result<(), ParseError> {
         // Note: our expression type might be fixed by our parent, but we still
         // need to make sure it matches the type associated with our operation.
         use BinaryOperator as BO;
         let upcast_id = id.upcast();
         let expr = &ctx.heap[id];
         let arg1_id = expr.left;
         let arg2_id = expr.right;
         debug_log!("Binary expr '{:?}': {}", expr.operation, upcast_id.index);
         debug_log!(" * Before:");
         debug_log!("   - Arg1 type: {}", self.debug_get_display_name(ctx, arg1_id));
         debug_log!("   - Arg2 type: {}", self.debug_get_display_name(ctx, arg2_id));
         debug_log!("   - Expr type: {}", self.debug_get_display_name(ctx, upcast_id));
         let (progress_expr, progress_arg1, progress_arg2) = match expr.operation {
             BO::Concatenate => {
                 // Two cases: if one of the arguments or the output type is a
                 // string, then all must be strings. Otherwise the arguments
                 // must be arraylike and the output will be a array.
                 let (expr_is_str, expr_is_not_str) = self.type_is_certainly_or_certainly_not_string(ctx, upcast_id);
                 let (arg1_is_str, arg1_is_not_str) = self.type_is_certainly_or_certainly_not_string(ctx, arg1_id);
                 let (arg2_is_str, arg2_is_not_str) = self.type_is_certainly_or_certainly_not_string(ctx, arg2_id);
                 let someone_is_str = expr_is_str || arg1_is_str || arg2_is_str;
                 let someone_is_not_str = expr_is_not_str || arg1_is_not_str || arg2_is_not_str;
                 // Note: this statement is an expression returning the progression bools
                 if someone_is_str {
                     // One of the arguments is a string, then all must be strings
                     self.apply_equal3_constraint(ctx, upcast_id, arg1_id, arg2_id, 0)?
                 } else {
                     let progress_expr = if someone_is_not_str {
                         // Output must be a normal array
                         self.apply_template_constraint(ctx, upcast_id, &ARRAY_TEMPLATE)?
                     } else {
                         // Output may still be anything
                         self.apply_template_constraint(ctx, upcast_id, &ARRAYLIKE_TEMPLATE)?
                     };
                     let progress_arg1 = self.apply_template_constraint(ctx, arg1_id, &ARRAYLIKE_TEMPLATE)?;
                     let progress_arg2 = self.apply_template_constraint(ctx, arg2_id, &ARRAYLIKE_TEMPLATE)?;
                     // If they're all arraylike, then we want the subtype to match
                     let (subtype_expr, subtype_arg1, subtype_arg2) =
                         self.apply_equal3_constraint(ctx, upcast_id, arg1_id, arg2_id, 1)?;
                     (progress_expr || subtype_expr, progress_arg1 || subtype_arg1, progress_arg2 || subtype_arg2)
+                }
             },
             BO::LogicalAnd => {
                 // Forced boolean on all
                 let progress_expr = self.apply_forced_constraint(ctx, upcast_id, &BOOL_TEMPLATE)?;
                 let progress_arg1 = self.apply_forced_constraint(ctx, upcast_id, &BOOL_TEMPLATE)?;
                 let progress_arg2 = self.apply_forced_constraint(ctx, upcast_id, &BOOL_TEMPLATE)?;
                 (progress_expr, progress_arg1, progress_arg2)
             },
             BO::LogicalOr => {
                 // Forced boolean on all
                 let progress_expr = self.apply_forced_constraint(ctx, upcast_id, &BOOL_TEMPLATE)?;
                 let progress_arg1 = self.apply_forced_constraint(ctx, arg1_id, &BOOL_TEMPLATE)?;
                 let progress_arg2 = self.apply_forced_constraint(ctx, arg2_id, &BOOL_TEMPLATE)?;
                 (progress_expr, progress_arg1, progress_arg2)
             },
             BO::BitwiseOr | BO::BitwiseXor | BO::BitwiseAnd | BO::Remainder | BO::ShiftLeft | BO::ShiftRight => {
                 // All equal of integer type
                 let progress_base = self.apply_template_constraint(ctx, upcast_id, &INTEGERLIKE_TEMPLATE)?;
                 let (progress_expr, progress_arg1, progress_arg2) =
                     self.apply_equal3_constraint(ctx, upcast_id, arg1_id, arg2_id, 0)?;
                 (progress_base || progress_expr, progress_base || progress_arg1, progress_base || progress_arg2)
             },
             BO::Equality | BO::Inequality => {
                 // Equal2 on args, forced boolean output
                 let progress_expr = self.apply_forced_constraint(ctx, upcast_id, &BOOL_TEMPLATE)?;
                 let (progress_arg1, progress_arg2) =
                     self.apply_equal2_constraint(ctx, upcast_id, arg1_id, 0, arg2_id, 0)?;
                 (progress_expr, progress_arg1, progress_arg2)
             },
             BO::LessThan | BO::GreaterThan | BO::LessThanEqual | BO::GreaterThanEqual => {
                 // Equal2 on args with numberlike type, forced boolean output
                 let progress_expr = self.apply_forced_constraint(ctx, upcast_id, &BOOL_TEMPLATE)?;
                 let progress_arg_base = self.apply_template_constraint(ctx, arg1_id, &NUMBERLIKE_TEMPLATE)?;
                 let (progress_arg1, progress_arg2) =
                     self.apply_equal2_constraint(ctx, upcast_id, arg1_id, 0, arg2_id, 0)?;
                 (progress_expr, progress_arg_base || progress_arg1, progress_arg_base || progress_arg2)
             },
             BO::Add | BO::Subtract | BO::Multiply | BO::Divide => {
                 // All equal of number type
                 let progress_base = self.apply_template_constraint(ctx, upcast_id, &NUMBERLIKE_TEMPLATE)?;
                 let (progress_expr, progress_arg1, progress_arg2) =
                     self.apply_equal3_constraint(ctx, upcast_id, arg1_id, arg2_id, 0)?;
                 (progress_base || progress_expr, progress_base || progress_arg1, progress_base || progress_arg2)
             },
         };
         debug_log!(" * After:");
         debug_log!("   - Arg1 type [{}]: {}", progress_arg1, self.debug_get_display_name(ctx, arg1_id));
         debug_log!("   - Arg2 type [{}]: {}", progress_arg2, self.debug_get_display_name(ctx, arg2_id));
         debug_log!("   - Expr type [{}]: {}", progress_expr, self.debug_get_display_name(ctx, upcast_id));
         if progress_expr { self.queue_expr_parent(ctx, upcast_id); }
         if progress_arg1 { self.queue_expr(ctx, arg1_id); }
         if progress_arg2 { self.queue_expr(ctx, arg2_id); }
         Ok(())
+    }
     fn progress_unary_expr(&mut self, ctx: &mut Ctx, id: UnaryExpressionId) -> Result<(), ParseError> {
         use UnaryOperator as UO;
         let upcast_id = id.upcast();
         let expr = &ctx.heap[id];
         let arg_id = expr.expression;
         debug_log!("Unary expr '{:?}': {}", expr.operation, upcast_id.index);
         debug_log!(" * Before:");
         debug_log!("   - Arg  type: {}", self.debug_get_display_name(ctx, arg_id));
         debug_log!("   - Expr type: {}", self.debug_get_display_name(ctx, upcast_id));
         let (progress_expr, progress_arg) = match expr.operation {
             UO::Positive | UO::Negative => {
                 // Equal types of numeric class
                 let progress_base = self.apply_template_constraint(ctx, upcast_id, &NUMBERLIKE_TEMPLATE)?;
                 let (progress_expr, progress_arg) =
                     self.apply_equal2_constraint(ctx, upcast_id, upcast_id, 0, arg_id, 0)?;
                 (progress_base || progress_expr, progress_base || progress_arg)
             },
             UO::BitwiseNot => {
                 // Equal types of integer class
                 let progress_base = self.apply_template_constraint(ctx, upcast_id, &INTEGERLIKE_TEMPLATE)?;
                 let (progress_expr, progress_arg) =
                     self.apply_equal2_constraint(ctx, upcast_id, upcast_id, 0, arg_id, 0)?;
                 (progress_base || progress_expr, progress_base || progress_arg)
             },
             UO::LogicalNot => {
                 // Both bools
                 let progress_expr = self.apply_forced_constraint(ctx, upcast_id, &BOOL_TEMPLATE)?;
                 let progress_arg = self.apply_forced_constraint(ctx, upcast_id, &BOOL_TEMPLATE)?;
                 (progress_expr, progress_arg)
+            }
         };
         debug_log!(" * After:");
         debug_log!("   - Arg  type [{}]: {}", progress_arg, self.debug_get_display_name(ctx, arg_id));
         debug_log!("   - Expr type [{}]: {}", progress_expr, self.debug_get_display_name(ctx, upcast_id));
         if progress_expr { self.queue_expr_parent(ctx, upcast_id); }
         if progress_arg { self.queue_expr(ctx, arg_id); }
         Ok(())
+    }
     fn progress_indexing_expr(&mut self, ctx: &mut Ctx, id: IndexingExpressionId) -> Result<(), ParseError> {
         let upcast_id = id.upcast();
         let expr = &ctx.heap[id];
         let subject_id = expr.subject;
         let index_id = expr.index;
         debug_log!("Indexing expr: {}", upcast_id.index);
         debug_log!(" * Before:");
         debug_log!("   - Subject type: {}", self.debug_get_display_name(ctx, subject_id));
         debug_log!("   - Index   type: {}", self.debug_get_display_name(ctx, index_id));
         debug_log!("   - Expr    type: {}", self.debug_get_display_name(ctx, upcast_id));
         // Make sure subject is arraylike and index is integerlike
         let progress_subject_base = self.apply_template_constraint(ctx, subject_id, &ARRAYLIKE_TEMPLATE)?;
         let progress_index = self.apply_template_constraint(ctx, index_id, &INTEGERLIKE_TEMPLATE)?;
         // Make sure if output is of T then subject is Array<T>
         let (progress_expr, progress_subject) =
             self.apply_equal2_constraint(ctx, upcast_id, upcast_id, 0, subject_id, 1)?;
         debug_log!(" * After:");
         debug_log!("   - Subject type [{}]: {}", progress_subject_base || progress_subject, self.debug_get_display_name(ctx, subject_id));
         debug_log!("   - Index   type [{}]: {}", progress_index, self.debug_get_display_name(ctx, index_id));
         debug_log!("   - Expr    type [{}]: {}", progress_expr, self.debug_get_display_name(ctx, upcast_id));
         if progress_expr { self.queue_expr_parent(ctx, upcast_id); }
         if progress_subject_base || progress_subject { self.queue_expr(ctx, subject_id); }
         if progress_index { self.queue_expr(ctx, index_id); }
         Ok(())
+    }
     fn progress_slicing_expr(&mut self, ctx: &mut Ctx, id: SlicingExpressionId) -> Result<(), ParseError> {
         let upcast_id = id.upcast();
         let expr = &ctx.heap[id];
         let subject_id = expr.subject;
         let from_id = expr.from_index;
         let to_id = expr.to_index;
         debug_log!("Slicing expr: {}", upcast_id.index);
         debug_log!(" * Before:");
         debug_log!("   - Subject type: {}", self.debug_get_display_name(ctx, subject_id));
         debug_log!("   - FromIdx type: {}", self.debug_get_display_name(ctx, from_id));
         debug_log!("   - ToIdx   type: {}", self.debug_get_display_name(ctx, to_id));
         debug_log!("   - Expr    type: {}", self.debug_get_display_name(ctx, upcast_id));
         // Make sure subject is arraylike and indices are of equal integerlike
         let progress_subject_base = self.apply_template_constraint(ctx, subject_id, &ARRAYLIKE_TEMPLATE)?;
         let progress_idx_base = self.apply_template_constraint(ctx, from_id, &INTEGERLIKE_TEMPLATE)?;
         let (progress_from, progress_to) = self.apply_equal2_constraint(ctx, upcast_id, from_id, 0, to_id, 0)?;
         let (progress_expr, progress_subject) = match self.type_is_certainly_or_certainly_not_string(ctx, subject_id) {
             (true, _) => {
                 // Certainly a string
                 (self.apply_forced_constraint(ctx, upcast_id, &STRING_TEMPLATE)?, false)
             },
             (_, true) => {
                 // Certainly not a string
                 let progress_expr_base = self.apply_template_constraint(ctx, upcast_id, &SLICE_TEMPLATE)?;
                 let (progress_expr, progress_subject) =
                     self.apply_equal2_constraint(ctx, upcast_id, upcast_id, 1, subject_id, 1)?;
                 (progress_expr_base || progress_expr, progress_subject)
             },
             _ => {
                 // Could be anything, at least attempt to progress subtype
                 let progress_expr_base = self.apply_template_constraint(ctx, upcast_id, &ARRAYLIKE_TEMPLATE)?;
                 let (progress_expr, progress_subject) =
                     self.apply_equal2_constraint(ctx, upcast_id, upcast_id, 1, subject_id, 1)?;
                 (progress_expr_base || progress_expr, progress_subject)
+            }
         };
         debug_log!(" * After:");
         debug_log!("   - Subject type [{}]: {}", progress_subject_base || progress_subject, self.debug_get_display_name(ctx, subject_id));
         debug_log!("   - FromIdx type [{}]: {}", progress_idx_base || progress_from, self.debug_get_display_name(ctx, from_id));
         debug_log!("   - ToIdx   type [{}]: {}", progress_idx_base || progress_to, self.debug_get_display_name(ctx, to_id));
         debug_log!("   - Expr    type [{}]: {}", progress_expr, self.debug_get_display_name(ctx, upcast_id));
         if progress_expr { self.queue_expr_parent(ctx, upcast_id); }
         if progress_subject_base || progress_subject { self.queue_expr(ctx, subject_id); }
         if progress_idx_base || progress_from { self.queue_expr(ctx, from_id); }
         if progress_idx_base || progress_to { self.queue_expr(ctx, to_id); }
         Ok(())
+    }
     fn progress_select_expr(&mut self, ctx: &mut Ctx, id: SelectExpressionId) -> Result<(), ParseError> {
         let upcast_id = id.upcast();
         debug_log!("Select expr: {}", upcast_id.index);
         debug_log!(" * Before:");
         debug_log!("   - Subject type: {}", self.debug_get_display_name(ctx, ctx.heap[id].subject));
         debug_log!("   - Expr    type: {}", self.debug_get_display_name(ctx, upcast_id));
         let subject_id = ctx.heap[id].subject;
         let subject_expr_idx = ctx.heap[subject_id].get_unique_id_in_definition();
         let select_expr = &ctx.heap[id];
         let expr_idx = select_expr.unique_id_in_definition;
         let infer_expr = &self.expr_types[expr_idx as usize];
         let extra_idx = infer_expr.extra_data_idx;
         fn determine_inference_type_instance<'a>(types: &'a TypeTable, infer_type: &InferenceType) -> Result<Option<&'a DefinedType>, ()> {
             for part in &infer_type.parts {
                 if part.is_marker() || !part.is_concrete() {
                     continue;
+                }
                 // Part is concrete, check if it is an instance of something
                 if let InferenceTypePart::Instance(definition_id, _num_sub) = part {
                     // Lookup type definition and ensure the specified field
                     // name exists on the struct
                     let definition = types.get_base_definition(definition_id);
                     debug_assert!(definition.is_some());
                     let definition = definition.unwrap();
                     return Ok(Some(definition))
                 } else {
                     // Expected an instance of something
                     return Err(())
+                }
+            }
             // Nothing is concrete yet
             Ok(None)
+        }
         if infer_expr.field_or_monomorph_idx < 0 {
             // We don't know the field or the definition it is pointing to yet
             // Not yet known, check if we can determine it
             let subject_type = &self.expr_types[subject_expr_idx as usize].expr_type;
             let type_def = determine_inference_type_instance(&ctx.types, subject_type);
             match type_def {
                 Ok(Some(type_def)) => {
                     // Subject type is known, check if it is a
                     // struct and the field exists on the struct
                     let struct_def = if let DefinedTypeVariant::Struct(struct_def) = &type_def.definition {
                         struct_def
                     } else {
                         return Err(ParseError::new_error_at_span(
                             &ctx.module().source, select_expr.field_name.span, format!(
                                 "Can only apply field access to structs, got a subject of type '{}'",
                                 subject_type.display_name(&ctx.heap)
+                            )
                         ));
                     };
                     let mut struct_def_id = None;
                     for (field_def_idx, field_def) in struct_def.fields.iter().enumerate() {
                         if field_def.identifier == select_expr.field_name {
                             // Set field definition and index
                             let infer_expr = &mut self.expr_types[expr_idx as usize];
                             infer_expr.field_or_monomorph_idx = field_def_idx as i32;
                             struct_def_id = Some(type_def.ast_definition);
                             break;
+                        }
+                    }
                     if struct_def_id.is_none() {
                         let ast_struct_def = ctx.heap[type_def.ast_definition].as_struct();
                         return Err(ParseError::new_error_at_span(
                             &ctx.module().source, select_expr.field_name.span, format!(
                                 "this field does not exist on the struct '{}'",
                                 ast_struct_def.identifier.value.as_str()
+                            )
                         ))
+                    }
                     // Encountered definition and field index for the
                     // first time
                     self.insert_initial_select_polymorph_data(ctx, id, struct_def_id.unwrap());
                 },
                 Ok(None) => {
                     // Type of subject is not yet known, so we
                     // cannot make any progress yet
                     return Ok(())
                 },
                 Err(()) => {
                     return Err(ParseError::new_error_at_span(
                         &ctx.module().source, select_expr.field_name.span, format!(
                             "Can only apply field access to structs, got a subject of type '{}'",
                             subject_type.display_name(&ctx.heap)
+                        )
                     ));
+                }
+            }
+        }
         // If here then field index is known, and the referenced struct type
         // information is inserted into `extra_data`. Check to see if we can
         // do some mutual inference.
         let poly_data = &mut self.extra_data[extra_idx as usize];
         let mut poly_progress = HashSet::new();
         // Apply to struct's type
         let signature_type: *mut _ = &mut poly_data.embedded[0];
         let subject_type: *mut _ = &mut self.expr_types[subject_expr_idx as usize].expr_type;
         let (_, progress_subject) = Self::apply_equal2_signature_constraint(
             ctx, upcast_id, Some(subject_id), poly_data, &mut poly_progress,
             signature_type, 0, subject_type, 0
         )?;
         if progress_subject {
             self.expr_queued.push_back(subject_expr_idx);
+        }
         // Apply to field's type
         let signature_type: *mut _ = &mut poly_data.returned;
         let expr_type: *mut _ = &mut self.expr_types[expr_idx as usize].expr_type;
         let (_, progress_expr) = Self::apply_equal2_signature_constraint(
             ctx, upcast_id, None, poly_data, &mut poly_progress,
             signature_type, 0, expr_type, 0
         )?;
         if progress_expr {
             if let Some(parent_id) = ctx.heap[upcast_id].parent_expr_id() {
                 let parent_idx = ctx.heap[parent_id].get_unique_id_in_definition();
                 self.expr_queued.push_back(parent_idx);
+            }
+        }
         // Reapply progress in polymorphic variables to struct's type
         let signature_type: *mut _ = &mut poly_data.embedded[0];
         let subject_type: *mut _ = &mut self.expr_types[subject_expr_idx as usize].expr_type;
         let progress_subject = Self::apply_equal2_polyvar_constraint(
             poly_data, &poly_progress, signature_type, subject_type
         );
         let signature_type: *mut _ = &mut poly_data.returned;
         let expr_type: *mut _ = &mut self.expr_types[expr_idx as usize].expr_type;
         let progress_expr = Self::apply_equal2_polyvar_constraint(
             poly_data, &poly_progress, signature_type, expr_type
         );
         if progress_subject { self.queue_expr(ctx, subject_id); }
         if progress_expr { self.queue_expr_parent(ctx, upcast_id); }
         debug_log!(" * After:");
         debug_log!("   - Subject type [{}]: {}", progress_subject, self.debug_get_display_name(ctx, subject_id));
         debug_log!("   - Expr    type [{}]: {}", progress_expr, self.debug_get_display_name(ctx, upcast_id));
         Ok(())
+    }
     fn progress_literal_expr(&mut self, ctx: &mut Ctx, id: LiteralExpressionId) -> Result<(), ParseError> {
         let upcast_id = id.upcast();
         let expr = &ctx.heap[id];
         let expr_idx = expr.unique_id_in_definition;
         let extra_idx = self.expr_types[expr_idx as usize].extra_data_idx;
         debug_log!("Literal expr: {}", upcast_id.index);
         debug_log!(" * Before:");
         debug_log!("   - Expr type: {}", self.debug_get_display_name(ctx, upcast_id));
         let progress_expr = match &expr.value {
             Literal::Null => {
                 self.apply_template_constraint(ctx, upcast_id, &MESSAGE_TEMPLATE)?
             },
             Literal::Integer(_) => {
                 self.apply_template_constraint(ctx, upcast_id, &INTEGERLIKE_TEMPLATE)?
             },
             Literal::True | Literal::False => {
                 self.apply_forced_constraint(ctx, upcast_id, &BOOL_TEMPLATE)?
             },
             Literal::Character(_) => {
                 self.apply_forced_constraint(ctx, upcast_id, &CHARACTER_TEMPLATE)?
             },
             Literal::String(_) => {
                 self.apply_forced_constraint(ctx, upcast_id, &STRING_TEMPLATE)?
             },
             Literal::Struct(data) => {
                 let extra = &mut self.extra_data[extra_idx as usize];
                 for _poly in &extra.poly_vars {
                     debug_log!(" * Poly: {}", _poly.display_name(&ctx.heap));
+                }
                 let mut poly_progress = HashSet::new();
                 debug_assert_eq!(extra.embedded.len(), data.fields.len());
                 debug_log!(" * During (inferring types from fields and struct type):");
                 // Mutually infer field signature/expression types
                 for (field_idx, field) in data.fields.iter().enumerate() {
                     let field_expr_id = field.value;
                     let field_expr_idx = ctx.heap[field_expr_id].get_unique_id_in_definition();
                     let signature_type: *mut _ = &mut extra.embedded[field_idx];
                     let field_type: *mut _ = &mut self.expr_types[field_expr_idx as usize].expr_type;
                     let (_, progress_arg) = Self::apply_equal2_signature_constraint(
                         ctx, upcast_id, Some(field_expr_id), extra, &mut poly_progress,
                         signature_type, 0, field_type, 0
                     )?;
                     debug_log!(
                         "   - Field {} type | sig: {}, field: {}", field_idx,
                         unsafe{&*signature_type}.display_name(&ctx.heap),
                         unsafe{&*field_type}.display_name(&ctx.heap)
                     );
                     if progress_arg {
                         self.expr_queued.push_back(field_expr_idx);
+                    }
+                }
                 debug_log!("   - Field poly progress | {:?}", poly_progress);
                 // Same for the type of the struct itself
                 let signature_type: *mut _ = &mut extra.returned;
                 let expr_type: *mut _ = &mut self.expr_types[expr_idx as usize].expr_type;
                 let (_, progress_expr) = Self::apply_equal2_signature_constraint(
                     ctx, upcast_id, None, extra, &mut poly_progress,
                     signature_type, 0, expr_type, 0
                 )?;
                 debug_log!(
                     "   - Ret type | sig: {}, expr: {}",
                     unsafe{&*signature_type}.display_name(&ctx.heap),
                     unsafe{&*expr_type}.display_name(&ctx.heap)
                 );
                 debug_log!("   - Ret poly progress | {:?}", poly_progress);
                 if progress_expr {
                     // TODO: @cleanup, cannot call utility self.queue_parent thingo
                     if let Some(parent_id) = ctx.heap[upcast_id].parent_expr_id() {
                         let parent_idx = ctx.heap[parent_id].get_unique_id_in_definition();
                         self.expr_queued.push_back(parent_idx);
+                    }
+                }
                 // Check which expressions use the polymorphic arguments. If the
                 // polymorphic variables have been progressed then we try to
                 // progress them inside the expression as well.
                 debug_log!(" * During (reinferring from progressed polyvars):");
                 // For all field expressions
                 for field_idx in 0..extra.embedded.len() {
                     // Note: fields in extra.embedded are in the same order as
                     // they are specified in the literal. Whereas
                     // `data.fields[...].field_idx` points to the field in the
                     // struct definition.
                     let signature_type: *mut _ = &mut extra.embedded[field_idx];
                     let field_expr_id = data.fields[field_idx].value;
                     let field_expr_idx = ctx.heap[field_expr_id].get_unique_id_in_definition();
                     let field_type: *mut _ = &mut self.expr_types[field_expr_idx as usize].expr_type;
                     let progress_arg = Self::apply_equal2_polyvar_constraint(
                         extra, &poly_progress, signature_type, field_type
                     );
                     debug_log!(
                         "   - Field {} type | sig: {}, field: {}", field_idx,
                         unsafe{&*signature_type}.display_name(&ctx.heap),
                         unsafe{&*field_type}.display_name(&ctx.heap)
                     );
                     if progress_arg {
                         self.expr_queued.push_back(field_expr_idx);
+                    }
+                }
                 // For the return type
                 let signature_type: *mut _ = &mut extra.returned;
                 let expr_type: *mut _ = &mut self.expr_types[expr_idx as usize].expr_type;
                 let progress_expr = Self::apply_equal2_polyvar_constraint(
                     extra, &poly_progress, signature_type, expr_type
                 );
                 progress_expr
             },
             Literal::Enum(_) => {
                 let extra = &mut self.extra_data[extra_idx as usize];
                 for _poly in &extra.poly_vars {
                     debug_log!(" * Poly: {}", _poly.display_name(&ctx.heap));
+                }
                 let mut poly_progress = HashSet::new();
                 debug_log!(" * During (inferring types from return type)");
                 let signature_type: *mut _ = &mut extra.returned;
                 let expr_type: *mut _ = &mut self.expr_types[expr_idx as usize].expr_type;
                 let (_, progress_expr) = Self::apply_equal2_signature_constraint(
                     ctx, upcast_id, None, extra, &mut poly_progress,
                     signature_type, 0, expr_type, 0
                 )?;
                 debug_log!(
                     "   - Ret type | sig: {}, expr: {}",
                     unsafe{&*signature_type}.display_name(&ctx.heap),
                     unsafe{&*expr_type}.display_name(&ctx.heap)
                 );
                 if progress_expr {
                     // TODO: @cleanup
                     if let Some(parent_id) = ctx.heap[upcast_id].parent_expr_id() {
                         let parent_idx = ctx.heap[parent_id].get_unique_id_in_definition();
                         self.expr_queued.push_back(parent_idx);
+                    }
+                }
                 debug_log!(" * During (reinferring from progress polyvars):");
                 let progress_expr = Self::apply_equal2_polyvar_constraint(
                     extra, &poly_progress, signature_type, expr_type
                 );
                 progress_expr
             },
             Literal::Union(data) => {
                 let extra = &mut self.extra_data[extra_idx as usize];
                 for _poly in &extra.poly_vars {
                     debug_log!(" * Poly: {}", _poly.display_name(&ctx.heap));
+                }
                 let mut poly_progress = HashSet::new();
                 debug_assert_eq!(extra.embedded.len(), data.values.len());
                 debug_log!(" * During (inferring types from variant values and union type):");
                 // Mutually infer union variant values
                 for (value_idx, value_expr_id) in data.values.iter().enumerate() {
                     let value_expr_id = *value_expr_id;
                     let value_expr_idx = ctx.heap[value_expr_id].get_unique_id_in_definition();
                     let signature_type: *mut _ = &mut extra.embedded[value_idx];
                     let value_type: *mut _ = &mut self.expr_types[value_expr_idx as usize].expr_type;
                     let (_, progress_arg) = Self::apply_equal2_signature_constraint(
                         ctx, upcast_id, Some(value_expr_id), extra, &mut poly_progress,
                         signature_type, 0, value_type, 0
                     )?;
                     debug_log!(
                         "   - Value {} type | sig: {}, field: {}", value_idx,
                         unsafe{&*signature_type}.display_name(&ctx.heap),
                         unsafe{&*value_type}.display_name(&ctx.heap)
                     );
                     if progress_arg {
                         self.expr_queued.push_back(value_expr_idx);
+                    }
+                }
                 debug_log!("   - Field poly progress | {:?}", poly_progress);
                 // Infer type of union itself
                 let signature_type: *mut _ = &mut extra.returned;
                 let expr_type: *mut _ = &mut self.expr_types[expr_idx as usize].expr_type;
                 let (_, progress_expr) = Self::apply_equal2_signature_constraint(
                     ctx, upcast_id, None, extra, &mut poly_progress,
                     signature_type, 0, expr_type, 0
                 )?;
                 debug_log!(
                     "   - Ret type | sig: {}, expr: {}",
                     unsafe{&*signature_type}.display_name(&ctx.heap),
                     unsafe{&*expr_type}.display_name(&ctx.heap)
                 );
                 debug_log!("   - Ret poly progress | {:?}", poly_progress);
                 if progress_expr {
                     // TODO: @cleanup, borrowing rules
                     if let Some(parent_id) = ctx.heap[upcast_id].parent_expr_id() {
                         let parent_idx = ctx.heap[parent_id].get_unique_id_in_definition();
                         self.expr_queued.push_back(parent_idx);
+                    }
+                }
                 debug_log!(" * During (reinferring from progress polyvars):");
                 // For all embedded values of the union variant
                 for value_idx in 0..extra.embedded.len() {
                     let signature_type: *mut _ = &mut extra.embedded[value_idx];
                     let value_expr_id = data.values[value_idx];
                     let value_expr_idx = ctx.heap[value_expr_id].get_unique_id_in_definition();
                     let value_type: *mut _ = &mut self.expr_types[value_expr_idx as usize].expr_type;
                     let progress_arg = Self::apply_equal2_polyvar_constraint(
                         extra, &poly_progress, signature_type, value_type
                     );
                     debug_log!(
                         "   - Value {} type | sig: {}, value: {}", value_idx,
                         unsafe{&*signature_type}.display_name(&ctx.heap),
                         unsafe{&*value_type}.display_name(&ctx.heap)
                     );
                     if progress_arg {
                         self.expr_queued.push_back(value_expr_idx);
+                    }
+                }
                 // And for the union type itself
                 let signature_type: *mut _ = &mut extra.returned;
                 let expr_type: *mut _ = &mut self.expr_types[expr_idx as usize].expr_type;
                 let progress_expr = Self::apply_equal2_polyvar_constraint(
                     extra, &poly_progress, signature_type, expr_type
                 );
                 progress_expr
             },
             Literal::Array(data) => {
                 let expr_elements = data.clone(); // TODO: @performance
                 debug_log!("Array expr ({} elements): {}", expr_elements.len(), upcast_id.index);
                 debug_log!(" * Before:");
                 debug_log!("   - Expr type: {}", self.debug_get_display_name(ctx, upcast_id));
                 // All elements should have an equal type
                 let progress = self.apply_equal_n_constraint(ctx, upcast_id, &expr_elements)?;
                 for (progress_arg, arg_id) in progress.iter().zip(expr_elements.iter()) {
                     if *progress_arg {
                         self.queue_expr(ctx, *arg_id);
+                    }
+                }
                 // And the output should be an array of the element types
                 let mut progress_expr = self.apply_template_constraint(ctx, upcast_id, &ARRAY_TEMPLATE)?;
                 if !expr_elements.is_empty() {
                     let first_arg_id = expr_elements[0];
                     let (inner_expr_progress, arg_progress) = self.apply_equal2_constraint(
                         ctx, upcast_id, upcast_id, 1, first_arg_id, 0
                     )?;
                     progress_expr = progress_expr || inner_expr_progress;
                     // Note that if the array type progressed the type of the arguments,
                     // then we should enqueue this progression function again
                     // TODO: @fix Make apply_equal_n accept a start idx as well
                     if arg_progress { self.queue_expr(ctx, upcast_id); }
+                }
                 debug_log!(" * After:");
                 debug_log!("   - Expr type [{}]: {}", progress_expr, self.debug_get_display_name(ctx, upcast_id));
                 progress_expr
             },
         };
         debug_log!(" * After:");
         debug_log!("   - Expr type: {}", self.debug_get_display_name(ctx, upcast_id));
         if progress_expr { self.queue_expr_parent(ctx, upcast_id); }
         Ok(())
+    }
     fn progress_cast_expr(&mut self, ctx: &mut Ctx, id: CastExpressionId) -> Result<(), ParseError> {
         let upcast_id = id.upcast();
         let expr = &ctx.heap[id];
         let expr_idx = expr.unique_id_in_definition;
         debug_log!("Casting expr: {}", upcast_id.index);
         debug_log!(" * Before:");
         debug_log!("   - Expr type:    {}", self.debug_get_display_name(ctx, upcast_id));
         debug_log!("   - Subject type: {}", self.debug_get_display_name(ctx, expr.subject));
         // The cast expression might have its output type fixed by the
         // programmer, so apply that type to the output. Apart from that casting
         // acts like a blocker for two-way inference. So we'll just have to wait
         // until we know if the cast is valid.
         // TODO: Another thing that has to be updated the moment the type
         //  inferencer is fully index/job-based
         let infer_type = self.determine_inference_type_from_parser_type_elements(&expr.to_type.elements, true);
         let expr_progress = self.apply_template_constraint(ctx, upcast_id, &infer_type.parts)?;
         if expr_progress {
             self.queue_expr_parent(ctx, upcast_id);
+        }
         // Check if the two types are compatible
         debug_log!(" * After:");
         debug_log!("   - Expr type [{}]: {}", expr_progress, self.debug_get_display_name(ctx, upcast_id));
         debug_log!("   - Note that the subject type can never be inferred");
         debug_log!(" * Decision:");
         let subject_idx = ctx.heap[expr.subject].get_unique_id_in_definition();
         let expr_type = &self.expr_types[expr_idx as usize].expr_type;
         let subject_type = &self.expr_types[subject_idx as usize].expr_type;
         if !expr_type.is_done || !subject_type.is_done {
             // Not yet done
             debug_log!("   - Casting is valid: unknown as the types are not yet complete");
             return Ok(())
+        }
         // Valid casts: (bool, integer, character) can always be cast to one
         // another. A cast from a type to itself is also valid.
         fn is_bool_int_or_char(parts: &[InferenceTypePart]) -> bool {
             return parts.len() == 1 && (
                 parts[0] == InferenceTypePart::Bool ||
                 parts[0] == InferenceTypePart::Character ||
                 parts[0].is_concrete_integer()
             );
+        }
         let is_valid = if is_bool_int_or_char(&expr_type.parts) && is_bool_int_or_char(&subject_type.parts) {
             true
         } else if expr_type.parts == subject_type.parts {
             true
         } else {
             false
         };
         debug_log!("   - Casting is valid: {}", is_valid);
         if !is_valid {
             let cast_expr = &ctx.heap[id];
             let subject_expr = &ctx.heap[cast_expr.subject];
             return Err(ParseError::new_error_str_at_span(
                 &ctx.module().source, cast_expr.full_span, "invalid casting operation"
             ).with_info_at_span(
                 &ctx.module().source, subject_expr.full_span(), format!(
                     "cannot cast the argument type '{}' to the cast type '{}'",
                     subject_type.display_name(&ctx.heap),
                     expr_type.display_name(&ctx.heap)
+                )
             ));
+        }
         Ok(())
+    }
     // TODO: @cleanup, see how this can be cleaned up once I implement
     //  polymorphic struct/enum/union literals. These likely follow the same
     //  pattern as here.
     fn progress_call_expr(&mut self, ctx: &mut Ctx, id: CallExpressionId) -> Result<(), ParseError> {
         let upcast_id = id.upcast();
         let expr = &ctx.heap[id];
         let expr_idx = expr.unique_id_in_definition;
         let extra_idx = self.expr_types[expr_idx as usize].extra_data_idx;
         debug_log!("Call expr '{}': {}", ctx.heap[expr.definition].identifier().value.as_str(), upcast_id.index);
         debug_log!(" * Before:");
         debug_log!("   - Expr type: {}", self.debug_get_display_name(ctx, upcast_id));
         debug_log!(" * During (inferring types from arguments and return type):");
         let extra = &mut self.extra_data[extra_idx as usize];
         // Check if we can make progress using the arguments and/or return types
         // while keeping track of the polyvars we've extended
         let mut poly_progress = HashSet::new();
         debug_assert_eq!(extra.embedded.len(), expr.arguments.len());
         for (call_arg_idx, arg_id) in expr.arguments.clone().into_iter().enumerate() {
             let arg_expr_idx = ctx.heap[arg_id].get_unique_id_in_definition();
             let signature_type: *mut _ = &mut extra.embedded[call_arg_idx];
             let argument_type: *mut _ = &mut self.expr_types[arg_expr_idx as usize].expr_type;
             let (_, progress_arg) = Self::apply_equal2_signature_constraint(
                 ctx, upcast_id, Some(arg_id), extra, &mut poly_progress,
                 signature_type, 0, argument_type, 0
             )?;
             debug_log!(
                 "   - Arg {} type | sig: {}, arg: {}", call_arg_idx,
                 unsafe{&*signature_type}.display_name(&ctx.heap),
                 unsafe{&*argument_type}.display_name(&ctx.heap));
             if progress_arg {
                 // Progressed argument expression
                 self.expr_queued.push_back(arg_expr_idx);
+            }
+        }
         // Do the same for the return type
         let signature_type: *mut _ = &mut extra.returned;
         let expr_type: *mut _ = &mut self.expr_types[expr_idx as usize].expr_type;
         let (_, progress_expr) = Self::apply_equal2_signature_constraint(
             ctx, upcast_id, None, extra, &mut poly_progress,
             signature_type, 0, expr_type, 0
         )?;
         debug_log!(
             "   - Ret type | sig: {}, expr: {}",
             unsafe{&*signature_type}.display_name(&ctx.heap),
             unsafe{&*expr_type}.display_name(&ctx.heap)
         );
         if progress_expr {
             // TODO: @cleanup, cannot call utility self.queue_parent thingo
             if let Some(parent_id) = ctx.heap[upcast_id].parent_expr_id() {
                 let parent_idx = ctx.heap[parent_id].get_unique_id_in_definition();
                 self.expr_queued.push_back(parent_idx);
+            }
+        }
         // If we did not have an error in the polymorph inference above, then
         // reapplying the polymorph type to each argument type and the return
         // type should always succeed.
         debug_log!(" * During (reinferring from progressed polyvars):");
         for (_poly_idx, _poly_var) in extra.poly_vars.iter().enumerate() {
             debug_log!("   - Poly {} | sig: {}", _poly_idx, _poly_var.display_name(&ctx.heap));
+        }
         // TODO: @performance If the algorithm is changed to be more "on demand
         //  argument re-evaluation", instead of "all-argument re-evaluation",
         //  then this is no longer true
         for arg_idx in 0..extra.embedded.len() {
             let signature_type: *mut _ = &mut extra.embedded[arg_idx];
             let arg_expr_id = expr.arguments[arg_idx];
             let arg_expr_idx = ctx.heap[arg_expr_id].get_unique_id_in_definition();
             let arg_type: *mut _ = &mut self.expr_types[arg_expr_idx as usize].expr_type;
             let progress_arg = Self::apply_equal2_polyvar_constraint(
                 extra, &poly_progress,
                 signature_type, arg_type
             );
             debug_log!(
                 "   - Arg {} type | sig: {}, arg: {}", arg_idx,
                 unsafe{&*signature_type}.display_name(&ctx.heap),
                 unsafe{&*arg_type}.display_name(&ctx.heap)
             );
             if progress_arg {
                 self.expr_queued.push_back(arg_expr_idx);
+            }
+        }
         // Once more for the return type
         let signature_type: *mut _ = &mut extra.returned;
         let ret_type: *mut _ = &mut self.expr_types[expr_idx as usize].expr_type;
         let progress_ret = Self::apply_equal2_polyvar_constraint(
             extra, &poly_progress, signature_type, ret_type
         );
         debug_log!(
             "   - Ret type | sig: {}, arg: {}",
             unsafe{&*signature_type}.display_name(&ctx.heap),
             unsafe{&*ret_type}.display_name(&ctx.heap)
         );
         if progress_ret {
             self.queue_expr_parent(ctx, upcast_id);
+        }
         debug_log!(" * After:");
         debug_log!("   - Expr type: {}", self.debug_get_display_name(ctx, upcast_id));
         Ok(())
+    }
     fn progress_variable_expr(&mut self, ctx: &mut Ctx, id: VariableExpressionId) -> Result<(), ParseError> {
         let upcast_id = id.upcast();
         let var_expr = &ctx.heap[id];
         let var_expr_idx = var_expr.unique_id_in_definition;
         let var_id = var_expr.declaration.unwrap();
         debug_log!("Variable expr '{}': {}", ctx.heap[var_id].identifier.value.as_str(), upcast_id.index);
         debug_log!(" * Before:");
         debug_log!("   - Var  type: {}", self.var_types.get(&var_id).unwrap().var_type.display_name(&ctx.heap));
         debug_log!("   - Expr type: {}", self.debug_get_display_name(ctx, upcast_id));
         // Retrieve shared variable type and expression type and apply inference
         let var_data = self.var_types.get_mut(&var_id).unwrap();
         let expr_type = &mut self.expr_types[var_expr_idx as usize].expr_type;
         let infer_res = unsafe{ InferenceType::infer_subtrees_for_both_types(
             &mut var_data.var_type as *mut _, 0, expr_type, 0
         ) };
         if infer_res == DualInferenceResult::Incompatible {
             let var_decl = &ctx.heap[var_id];
             return Err(ParseError::new_error_at_span(
                 &ctx.module().source, var_decl.identifier.span, format!(
                     "Conflicting types for this variable, previously assigned the type '{}'",
                     var_data.var_type.display_name(&ctx.heap)
+                )
             ).with_info_at_span(
                 &ctx.module().source, var_expr.identifier.span, format!(
                     "But inferred to have incompatible type '{}' here",
                     expr_type.display_name(&ctx.heap)
+                )
             ))
+        }
         let progress_var = infer_res.modified_lhs();
         let progress_expr = infer_res.modified_rhs();
         if progress_var {
             // Let other variable expressions using this type progress as well
             for other_expr in var_data.used_at.iter() {
                 if *other_expr != upcast_id {
                     let other_expr_idx = ctx.heap[*other_expr].get_unique_id_in_definition();
                     self.expr_queued.push_back(other_expr_idx);
+                }
+            }
             // Let a linked port know that our type has updated
             if let Some(linked_id) = var_data.linked_var {
                 // Only perform one-way inference to prevent updating our type,
                 // this would lead to an inconsistency in the type inference
                 // algorithm otherwise.
                 let var_type: *mut _ = &mut var_data.var_type;
                 let link_data = self.var_types.get_mut(&linked_id).unwrap();
                 debug_assert!(
                     unsafe{&*var_type}.parts[0] == InferenceTypePart::Input ||
                     unsafe{&*var_type}.parts[0] == InferenceTypePart::Output
                 );
                 debug_assert!(
                     link_data.var_type.parts[0] == InferenceTypePart::Input ||
                     link_data.var_type.parts[0] == InferenceTypePart::Output
                 );
                 match InferenceType::infer_subtree_for_single_type(&mut link_data.var_type, 1, &unsafe{&*var_type}.parts, 1, false) {
                     SingleInferenceResult::Modified => {
                         for other_expr in &link_data.used_at {
                             let other_expr_idx = ctx.heap[*other_expr].get_unique_id_in_definition();
                             self.expr_queued.push_back(other_expr_idx);
+                        }
                     },
                     SingleInferenceResult::Unmodified => {},
                     SingleInferenceResult::Incompatible => {
                         let var_data = self.var_types.get(&var_id).unwrap();
                         let link_data = self.var_types.get(&linked_id).unwrap();
                         let var_decl = &ctx.heap[var_id];
                         let link_decl = &ctx.heap[linked_id];
                         return Err(ParseError::new_error_at_span(
                             &ctx.module().source, var_decl.identifier.span, format!(
                                 "Conflicting types for this variable, assigned the type '{}'",
                                 var_data.var_type.display_name(&ctx.heap)
+                            )
                         ).with_info_at_span(
                             &ctx.module().source, link_decl.identifier.span, format!(
                                 "Because it is incompatible with this variable, assigned the type '{}'",
                                 link_data.var_type.display_name(&ctx.heap)
+                            )
                         ));
+                    }
+                }
+            }
+        }
         if progress_expr { self.queue_expr_parent(ctx, upcast_id); }
         debug_log!(" * After:");
         debug_log!("   - Var  type [{}]: {}", progress_var, self.var_types.get(&var_id).unwrap().var_type.display_name(&ctx.heap));
         debug_log!("   - Expr type [{}]: {}", progress_expr, self.debug_get_display_name(ctx, upcast_id));
         Ok(())
+    }
     fn queue_expr_parent(&mut self, ctx: &Ctx, expr_id: ExpressionId) {
         if let ExpressionParent::Expression(parent_expr_id, _) = &ctx.heap[expr_id].parent() {
             let expr_idx = ctx.heap[*parent_expr_id].get_unique_id_in_definition();
             self.expr_queued.push_back(expr_idx);
+        }
+    }
     fn queue_expr(&mut self, ctx: &Ctx, expr_id: ExpressionId) {
         let expr_idx = ctx.heap[expr_id].get_unique_id_in_definition();
         self.expr_queued.push_back(expr_idx);
+    }
     // first returned is certainly string, second is certainly not
     fn type_is_certainly_or_certainly_not_string(&self, ctx: &Ctx, expr_id: ExpressionId) -> (bool, bool) {
         let expr_idx = ctx.heap[expr_id].get_unique_id_in_definition();
         let expr_type = &self.expr_types[expr_idx as usize].expr_type;
         if expr_type.is_done {
             if expr_type.parts[0] == InferenceTypePart::String {
                 return (true, false);
             } else {
                 return (false, true);
+            }
+        }
         (false, false)
+    }
     /// Applies a template type constraint: the type associated with the
     /// supplied expression will be molded into the provided `template`. But
     /// will be considered valid if the template could've been molded into the
     /// expression type as well. Hence the template may be fully specified (e.g.
     /// a bool) or contain "inference" variables (e.g. an array of T)
     fn apply_template_constraint(
         &mut self, ctx: &Ctx, expr_id: ExpressionId, template: &[InferenceTypePart]
     ) -> Result<bool, ParseError> {
         let expr_idx = ctx.heap[expr_id].get_unique_id_in_definition(); // TODO: @Temp
         let expr_type = &mut self.expr_types[expr_idx as usize].expr_type;
         match InferenceType::infer_subtree_for_single_type(expr_type, 0, template, 0, false) {
             SingleInferenceResult::Modified => Ok(true),
             SingleInferenceResult::Unmodified => Ok(false),
             SingleInferenceResult::Incompatible => Err(
                 self.construct_template_type_error(ctx, expr_id, template)
+            )
+        }
+    }
     fn apply_template_constraint_to_types(
         to_infer: *mut InferenceType, to_infer_start_idx: usize,
         template: &[InferenceTypePart], template_start_idx: usize
     ) -> Result<bool, ()> {
         match InferenceType::infer_subtree_for_single_type(
             unsafe{ &mut *to_infer }, to_infer_start_idx,
             template, template_start_idx, false
         ) {
             SingleInferenceResult::Modified => Ok(true),
             SingleInferenceResult::Unmodified => Ok(false),
             SingleInferenceResult::Incompatible => Err(()),
+        }
+    }
     /// Applies a forced constraint: the supplied expression's type MUST be
     /// inferred from the template, the other way around is considered invalid.
     fn apply_forced_constraint(
         &mut self, ctx: &Ctx, expr_id: ExpressionId, template: &[InferenceTypePart]
     ) -> Result<bool, ParseError> {
         let expr_idx = ctx.heap[expr_id].get_unique_id_in_definition();
         let expr_type = &mut self.expr_types[expr_idx as usize].expr_type;
         match InferenceType::infer_subtree_for_single_type(expr_type, 0, template, 0, true) {
             SingleInferenceResult::Modified => Ok(true),
             SingleInferenceResult::Unmodified => Ok(false),
             SingleInferenceResult::Incompatible => Err(
                 self.construct_template_type_error(ctx, expr_id, template)
+            )
+        }
+    }
     /// Applies a type constraint that expects the two provided types to be
     /// equal. We attempt to make progress in inferring the types. If the call
     /// is successful then the composition of all types are made equal.
     /// The "parent" `expr_id` is provided to construct errors.
     fn apply_equal2_constraint(
         &mut self, ctx: &Ctx, expr_id: ExpressionId,
         arg1_id: ExpressionId, arg1_start_idx: usize,
         arg2_id: ExpressionId, arg2_start_idx: usize
     ) -> Result<(bool, bool), ParseError> {
         let arg1_expr_idx = ctx.heap[arg1_id].get_unique_id_in_definition(); // TODO: @Temp
         let arg2_expr_idx = ctx.heap[arg2_id].get_unique_id_in_definition();
         let arg1_type: *mut _ = &mut self.expr_types[arg1_expr_idx as usize].expr_type;
         let arg2_type: *mut _ = &mut self.expr_types[arg2_expr_idx as usize].expr_type;
         let infer_res = unsafe{ InferenceType::infer_subtrees_for_both_types(
             arg1_type, arg1_start_idx,
             arg2_type, arg2_start_idx
         ) };
         if infer_res == DualInferenceResult::Incompatible {
             return Err(self.construct_arg_type_error(ctx, expr_id, arg1_id, arg2_id));
+        }
         Ok((infer_res.modified_lhs(), infer_res.modified_rhs()))
+    }
     /// Applies an equal2 constraint between a signature type (e.g. a function
     /// argument or struct field) and an expression whose type should match that
     /// expression. If we make progress on the signature, then we try to see if
     /// any of the embedded polymorphic types can be progressed.
     ///
     /// `outer_expr_id` is the main expression we're progressing (e.g. a
     /// function call), while `expr_id` is the embedded expression we're
     /// matching against the signature. `expression_type` and
     /// `expression_start_idx` belong to `expr_id`.
     fn apply_equal2_signature_constraint(
         ctx: &Ctx, outer_expr_id: ExpressionId, expr_id: Option<ExpressionId>,
         polymorph_data: &mut ExtraData, polymorph_progress: &mut HashSet<u32>,
         signature_type: *mut InferenceType, signature_start_idx: usize,
         expression_type: *mut InferenceType, expression_start_idx: usize
     ) -> Result<(bool, bool), ParseError> {
         // Safety: all pointers distinct
         // Infer the signature and expression type
         let infer_res = unsafe {
             InferenceType::infer_subtrees_for_both_types(
                 signature_type, signature_start_idx,
                 expression_type, expression_start_idx
+            )
         };
         if infer_res == DualInferenceResult::Incompatible {
             // TODO: Check if I still need to use this
             let outer_span = ctx.heap[outer_expr_id].full_span();
             let (span_name, span) = match expr_id {
                 Some(expr_id) => ("argument's", ctx.heap[expr_id].full_span()),
                 None => ("type's", outer_span)
             };
             let (signature_display_type, expression_display_type) = unsafe { (
                 (&*signature_type).display_name(&ctx.heap),
                 (&*expression_type).display_name(&ctx.heap)
             ) };
             return Err(ParseError::new_error_str_at_span(
                 &ctx.module().source, outer_span,
                 "failed to fully resolve the types of this expression"
             ).with_info_at_span(
                 &ctx.module().source, span, format!(
                     "because the {} signature has been resolved to '{}', but the expression has been resolved to '{}'",
                     span_name, signature_display_type, expression_display_type
+                )
             ));
+        }
         // Try to see if we can progress any of the polymorphic variables
         let progress_sig = infer_res.modified_lhs();
         let progress_expr = infer_res.modified_rhs();
         if progress_sig {
             let signature_type = unsafe{&mut *signature_type};
             debug_assert!(
                 signature_type.has_marker,
                 "made progress on signature type, but it doesn't have a marker"
             );
             for (poly_idx, poly_section) in signature_type.marker_iter() {
                 let polymorph_type = &mut polymorph_data.poly_vars[poly_idx as usize];
                 match Self::apply_template_constraint_to_types(
                     polymorph_type, 0, poly_section, 0
                 ) {
                     Ok(true) => { polymorph_progress.insert(poly_idx); },
                     Ok(false) => {},
                     Err(()) => { return Err(Self::construct_poly_arg_error(ctx, polymorph_data, outer_expr_id))}
+                }
+            }
+        }
         Ok((progress_sig, progress_expr))
+    }
     /// Applies equal2 constraints on the signature type for each of the
     /// polymorphic variables. If the signature type is progressed then we
     /// progress the expression type as well.
     ///
     /// This function assumes that the polymorphic variables have already been
     /// progressed as far as possible by calling
     /// `apply_equal2_signature_constraint`. As such, we expect to not encounter
     /// any errors.
     ///
     /// This function returns true if the expression's type has been progressed
     fn apply_equal2_polyvar_constraint(
         polymorph_data: &ExtraData, _polymorph_progress: &HashSet<u32>,
         signature_type: *mut InferenceType, expr_type: *mut InferenceType
     ) -> bool {
         // Safety: all pointers should be distinct
         //         polymorph_data containers may not be modified
         let signature_type = unsafe{&mut *signature_type};
         let expr_type = unsafe{&mut *expr_type};
         // Iterate through markers in signature type to try and make progress
         // on the polymorphic variable
         let mut seek_idx = 0;
         let mut modified_sig = false;
         while let Some((poly_idx, start_idx)) = signature_type.find_marker(seek_idx) {
             let end_idx = InferenceType::find_subtree_end_idx(&signature_type.parts, start_idx);
             // if polymorph_progress.contains(&poly_idx) {
                 // Need to match subtrees
                 let polymorph_type = &polymorph_data.poly_vars[poly_idx as usize];
                 let modified_at_marker = Self::apply_template_constraint_to_types(
                     signature_type, start_idx,
                     &polymorph_type.parts, 0
                 ).expect("no failure when applying polyvar constraints");
                 modified_sig = modified_sig || modified_at_marker;
             // }
             seek_idx = end_idx;
+        }
         // If we made any progress on the signature's type, then we also need to
         // apply it to the expression that is supposed to match the signature.
         if modified_sig {
             match InferenceType::infer_subtree_for_single_type(
                 expr_type, 0, &signature_type.parts, 0, true
             ) {
                 SingleInferenceResult::Modified => true,
                 SingleInferenceResult::Unmodified => false,
                 SingleInferenceResult::Incompatible =>
                     unreachable!("encountered failure while reapplying modified signature to expression after polyvar inference")
+            }
         } else {
             false
+        }
+    }
     /// Applies a type constraint that expects all three provided types to be
     /// equal. In case we can make progress in inferring the types then we
     /// attempt to do so. If the call is successful then the composition of all
     /// types is made equal.
     fn apply_equal3_constraint(
         &mut self, ctx: &Ctx, expr_id: ExpressionId,
         arg1_id: ExpressionId, arg2_id: ExpressionId,
         start_idx: usize
     ) -> Result<(bool, bool, bool), ParseError> {
         // Safety: all points are unique
         //         containers may not be modified
         let expr_expr_idx = ctx.heap[expr_id].get_unique_id_in_definition(); // TODO: @Temp
         let arg1_expr_idx = ctx.heap[arg1_id].get_unique_id_in_definition();
         let arg2_expr_idx = ctx.heap[arg2_id].get_unique_id_in_definition();
         let expr_type: *mut _ = &mut self.expr_types[expr_expr_idx as usize].expr_type;
         let arg1_type: *mut _ = &mut self.expr_types[arg1_expr_idx as usize].expr_type;
         let arg2_type: *mut _ = &mut self.expr_types[arg2_expr_idx as usize].expr_type;
         let expr_res = unsafe{
             InferenceType::infer_subtrees_for_both_types(expr_type, start_idx, arg1_type, start_idx)
         };
         if expr_res == DualInferenceResult::Incompatible {
             return Err(self.construct_expr_type_error(ctx, expr_id, arg1_id));
+        }
         let args_res = unsafe{
             InferenceType::infer_subtrees_for_both_types(arg1_type, start_idx, arg2_type, start_idx) };
         if args_res == DualInferenceResult::Incompatible {
             return Err(self.construct_arg_type_error(ctx, expr_id, arg1_id, arg2_id));
+        }
         // If all types are compatible, but the second call caused the arg1_type
         // to be expanded, then we must also assign this to expr_type.
         let mut progress_expr = expr_res.modified_lhs();
         let mut progress_arg1 = expr_res.modified_rhs();
         let progress_arg2 = args_res.modified_rhs();
         if args_res.modified_lhs() {
             unsafe {
                 let end_idx = InferenceType::find_subtree_end_idx(&(*arg2_type).parts, start_idx);
                 let subtree = &((*arg2_type).parts[start_idx..end_idx]);
                 (*expr_type).replace_subtree(start_idx, subtree);
+            }
             progress_expr = true;
             progress_arg1 = true;
+        }
         Ok((progress_expr, progress_arg1, progress_arg2))
+    }
     // TODO: @optimize Since we only deal with a single type this might be done
     //  a lot more efficiently, methinks (disregarding the allocations here)
     fn apply_equal_n_constraint(
         &mut self, ctx: &Ctx, expr_id: ExpressionId, args: &[ExpressionId],
     ) -> Result<Vec<bool>, ParseError> {
         // Early exit
         match args.len() {
 => return Ok(vec!()),         // nothing to progress
 => return Ok(vec![false]),    // only one type, so nothing to infer
             _ => {}
+        }
         let mut progress = Vec::new();
         progress.resize(args.len(), false);
         // Do pairwise inference, keep track of the last entry we made progress
         // on. Once done we need to update everything to the most-inferred type.
         let mut arg_iter = args.iter();
         let mut last_arg_id = *arg_iter.next().unwrap();
         let mut last_lhs_progressed = 0;
         let mut lhs_arg_idx = 0;
         while let Some(next_arg_id) = arg_iter.next() {
             let last_expr_idx = ctx.heap[last_arg_id].get_unique_id_in_definition(); // TODO: @Temp
             let next_expr_idx = ctx.heap[*next_arg_id].get_unique_id_in_definition();
             let last_type: *mut _ = &mut self.expr_types[last_expr_idx as usize].expr_type;
             let next_type: *mut _ = &mut self.expr_types[next_expr_idx as usize].expr_type;
             let res = unsafe {
                 InferenceType::infer_subtrees_for_both_types(last_type, 0, next_type, 0)
             };
             if res == DualInferenceResult::Incompatible {
                 return Err(self.construct_arg_type_error(ctx, expr_id, last_arg_id, *next_arg_id));
+            }
             if res.modified_lhs() {
                 // We re-inferred something on the left hand side, so everything
                 // up until now should be re-inferred.
                 progress[lhs_arg_idx] = true;
                 last_lhs_progressed = lhs_arg_idx;
+            }
             progress[lhs_arg_idx + 1] = res.modified_rhs();
             last_arg_id = *next_arg_id;
             lhs_arg_idx += 1;
+        }
         // Re-infer everything. Note that we do not need to re-infer the type
         // exactly at `last_lhs_progressed`, but only everything up to it.
         let last_arg_expr_idx = ctx.heap[*args.last().unwrap()].get_unique_id_in_definition();
         let last_type: *mut _ = &mut self.expr_types[last_arg_expr_idx as usize].expr_type;
         for arg_idx in 0..last_lhs_progressed {
             let other_arg_expr_idx = ctx.heap[args[arg_idx]].get_unique_id_in_definition();
             let arg_type: *mut _ = &mut self.expr_types[other_arg_expr_idx as usize].expr_type;
             unsafe{
                 (*arg_type).replace_subtree(0, &(*last_type).parts);
+            }
             progress[arg_idx] = true;
+        }
         Ok(progress)
+    }
     /// Determines the `InferenceType` for the expression based on the
     /// expression parent. Note that if the parent is another expression, we do
     /// not take special action, instead we let parent expressions fix the type
     /// of subexpressions before they have a chance to call this function.
     fn insert_initial_expr_inference_type(
         &mut self, ctx: &mut Ctx, expr_id: ExpressionId
     ) -> Result<(), ParseError> {
         use ExpressionParent as EP;
         use InferenceTypePart as ITP;
         let expr = &ctx.heap[expr_id];
         let inference_type = match expr.parent() {
             EP::None =>
                 // Should have been set by linker
                 unreachable!(),
             EP::ExpressionStmt(_) =>
                 // Determined during type inference
                 InferenceType::new(false, false, vec![ITP::Unknown]),
             EP::Expression(parent_id, idx_in_parent) => {
                 // If we are the test expression of a conditional expression,
                 // then we must resolve to a boolean
                 let is_conditional = if let Expression::Conditional(_) = &ctx.heap[*parent_id] {
                     true
                 } else {
                     false
                 };
                 if is_conditional && *idx_in_parent == 0 {
                     InferenceType::new(false, true, vec![ITP::Bool])
                 } else {
                     InferenceType::new(false, false, vec![ITP::Unknown])
+                }
             },
             EP::If(_) | EP::While(_) =>
                 // Must be a boolean
                 InferenceType::new(false, true, vec![ITP::Bool]),
             EP::Return(_) =>
                 // Must match the return type of the function
                 if let DefinitionType::Function(func_id) = self.definition_type {
                     debug_assert_eq!(ctx.heap[func_id].return_types.len(), 1);
                     let returned = &ctx.heap[func_id].return_types[0];
                     self.determine_inference_type_from_parser_type_elements(&returned.elements, true)
                 } else {
                     // Cannot happen: definition always set upon body traversal
                     // and "return" calls in components are illegal.
                     unreachable!();
                 },
             EP::New(_) =>
                 // Must be a component call, which we assign a "Void" return
                 // type
                 InferenceType::new(false, true, vec![ITP::Void]),
         };
         let infer_expr = &mut self.expr_types[expr.get_unique_id_in_definition() as usize];
         let needs_extra_data = match expr {
             Expression::Call(_) => true,
             Expression::Literal(expr) => match expr.value {
                 Literal::Enum(_) | Literal::Union(_) | Literal::Struct(_) => true,
                 _ => false,
             },
             Expression::Select(_) => true,
             _ => false,
         };
         if infer_expr.expr_id.is_invalid() {
             // Nothing is set yet
             infer_expr.expr_type = inference_type;
             infer_expr.expr_id = expr_id;
             if needs_extra_data {
                 let extra_idx = self.extra_data.len() as i32;
                 self.extra_data.push(ExtraData::default());
                 infer_expr.extra_data_idx = extra_idx;
+            }
         } else {
             // We already have an entry
             debug_assert!(false, "does this ever happen?");
             if let SingleInferenceResult::Incompatible = InferenceType::infer_subtree_for_single_type(
                 &mut infer_expr.expr_type, 0, &inference_type.parts, 0, false
             ) {
                 return Err(self.construct_expr_type_error(ctx, expr_id, expr_id));
+            }
             debug_assert!((infer_expr.extra_data_idx != -1) == needs_extra_data);
+        }
         Ok(())
+    }
     fn insert_initial_call_polymorph_data(
         &mut self, ctx: &mut Ctx, call_id: CallExpressionId
     ) {
         // Note: the polymorph variables may be partially specified and may
         // contain references to the wrapping definition's (i.e. the proctype
         // we are currently visiting) polymorphic arguments.
         //
         // The arguments of the call may refer to polymorphic variables in the
         // definition of the function we're calling, not of the wrapping
         // definition. We insert markers in these inferred types to be able to
         // map them back and forth to the polymorphic arguments of the function
         // we are calling.
         let call = &ctx.heap[call_id];
         let extra_data_idx = self.expr_types[call.unique_id_in_definition as usize].extra_data_idx; // TODO: @Temp
         debug_assert!(extra_data_idx != -1, "insert initial call polymorph data, no preallocated ExtraData");
         // Handle the polymorphic arguments (if there are any)
         let num_poly_args = call.parser_type.elements[0].variant.num_embedded();
         let mut poly_args = Vec::with_capacity(num_poly_args);
         for embedded_elements in call.parser_type.iter_embedded(0) {
             poly_args.push(self.determine_inference_type_from_parser_type_elements(embedded_elements, true));
+        }
         // Handle the arguments and return types
         let definition = &ctx.heap[call.definition];
         let (parameters, returned) = match definition {
             Definition::Component(definition) => {
                 debug_assert_eq!(poly_args.len(), definition.poly_vars.len());
                 (&definition.parameters, None)
             },
             Definition::Function(definition) => {
                 debug_assert_eq!(poly_args.len(), definition.poly_vars.len());
                 (&definition.parameters, Some(&definition.return_types))
             },
             Definition::Struct(_) | Definition::Enum(_) | Definition::Union(_) => {
                 unreachable!("insert_initial_call_polymorph data for non-procedure type");
             },
         };
         let mut parameter_types = Vec::with_capacity(parameters.len());
         for parameter_id in parameters.clone().into_iter() { // TODO: @Performance @Now
             let param = &ctx.heap[parameter_id];
             parameter_types.push(self.determine_inference_type_from_parser_type_elements(&param.parser_type.elements, false));
+        }
         let return_type = match returned {
             None => {
                 // Component, so returns a "Void"
                 InferenceType::new(false, true, vec![InferenceTypePart::Void])
             },
             Some(returned) => {
                 debug_assert_eq!(returned.len(), 1); // TODO: @ReturnTypes
                 let returned = &returned[0];
                 self.determine_inference_type_from_parser_type_elements(&returned.elements, false)
+            }
         };
         self.extra_data[extra_data_idx as usize] = ExtraData{
             expr_id: call_id.upcast(),
             definition_id: call.definition,
             poly_vars: poly_args,
             embedded: parameter_types,
             returned: return_type
         };
+    }
     fn insert_initial_struct_polymorph_data(
         &mut self, ctx: &mut Ctx, lit_id: LiteralExpressionId,
     ) {
         use InferenceTypePart as ITP;
         let literal = &ctx.heap[lit_id];
         let extra_data_idx = self.expr_types[literal.unique_id_in_definition as usize].extra_data_idx; // TODO: @Temp
         debug_assert!(extra_data_idx != -1, "initial struct polymorph data, but no preallocated ExtraData");
         let literal = ctx.heap[lit_id].value.as_struct();
         // Handle polymorphic arguments
         let num_embedded = literal.parser_type.elements[0].variant.num_embedded();
         let mut total_num_poly_parts = 0;
         let mut poly_args = Vec::with_capacity(num_embedded);
         for embedded_elements in literal.parser_type.iter_embedded(0) {
             let poly_type = self.determine_inference_type_from_parser_type_elements(embedded_elements, true);
             total_num_poly_parts += poly_type.parts.len();
             poly_args.push(poly_type);
+        }
         // Handle parser types on struct definition
         let defined_type = ctx.types.get_base_definition(&literal.definition).unwrap();
         let struct_type = defined_type.definition.as_struct();
         debug_assert_eq!(poly_args.len(), defined_type.poly_vars.len());
         // Note: programmer is capable of specifying fields in a struct literal
         // in a different order than on the definition. We take the literal-
         // specified order to be leading.
         let mut embedded_types = Vec::with_capacity(struct_type.fields.len());
         for lit_field in literal.fields.iter() {
             let def_field = &struct_type.fields[lit_field.field_idx];
             let inference_type = self.determine_inference_type_from_parser_type_elements(&def_field.parser_type.elements, false);
             embedded_types.push(inference_type);
+        }
         // Return type is the struct type itself, with the appropriate
         // polymorphic variables. So:
         // - 1 part for definition
         // - N_poly_arg marker parts for each polymorphic argument
         // - all the parts for the currently known polymorphic arguments
         let parts_reserved = 1 + poly_args.len() + total_num_poly_parts;
         let mut parts = Vec::with_capacity(parts_reserved);
         parts.push(ITP::Instance(literal.definition, poly_args.len() as u32));
         let mut return_type_done = true;
         for (poly_var_idx, poly_var) in poly_args.iter().enumerate() {
             if !poly_var.is_done { return_type_done = false; }
             parts.push(ITP::Marker(poly_var_idx as u32));
             parts.extend(poly_var.parts.iter().cloned());
+        }
         debug_assert_eq!(parts.len(), parts_reserved);
         let return_type = InferenceType::new(!poly_args.is_empty(), return_type_done, parts);
         self.extra_data[extra_data_idx as usize] = ExtraData{
             expr_id: lit_id.upcast(),
             definition_id: literal.definition,
             poly_vars: poly_args,
             embedded: embedded_types,
             returned: return_type,
         };
+    }
     /// Inserts the extra polymorphic data struct for enum expressions. These
     /// can never be determined from the enum itself, but may be inferred from
     /// the use of the enum.
     fn insert_initial_enum_polymorph_data(
         &mut self, ctx: &Ctx, lit_id: LiteralExpressionId
     ) {
         use InferenceTypePart as ITP;
         let literal = &ctx.heap[lit_id];
         let extra_data_idx = self.expr_types[literal.unique_id_in_definition as usize].extra_data_idx; // TODO: @Temp
         debug_assert!(extra_data_idx != -1, "initial enum polymorph data, but no preallocated ExtraData");
         let literal = ctx.heap[lit_id].value.as_enum();
         // Handle polymorphic arguments to the enum
         let num_poly_args = literal.parser_type.elements[0].variant.num_embedded();
         let mut total_num_poly_parts = 0;
         let mut poly_args = Vec::with_capacity(num_poly_args);
         for embedded_elements in literal.parser_type.iter_embedded(0) {
             let poly_type = self.determine_inference_type_from_parser_type_elements(embedded_elements, true);
             total_num_poly_parts += poly_type.parts.len();
             poly_args.push(poly_type);
+        }
         // Handle enum type itself
         let parts_reserved = 1 + poly_args.len() + total_num_poly_parts;
         let mut parts = Vec::with_capacity(parts_reserved);
         parts.push(ITP::Instance(literal.definition, poly_args.len() as u32));
         let mut enum_type_done = true;
         for (poly_var_idx, poly_var) in poly_args.iter().enumerate() {
             if !poly_var.is_done { enum_type_done = false; }
             parts.push(ITP::Marker(poly_var_idx as u32));
             parts.extend(poly_var.parts.iter().cloned());
+        }
         debug_assert_eq!(parts.len(), parts_reserved);
         let enum_type = InferenceType::new(!poly_args.is_empty(), enum_type_done, parts);
         self.extra_data[extra_data_idx as usize] = ExtraData{
             expr_id: lit_id.upcast(),
             definition_id: literal.definition,
             poly_vars: poly_args,
             embedded: Vec::new(),
             returned: enum_type,
         };
+    }
     /// Inserts the extra polymorphic data struct for unions. The polymorphic
     /// arguments may be partially determined from embedded values in the union.
     fn insert_initial_union_polymorph_data(
         &mut self, ctx: &Ctx, lit_id: LiteralExpressionId
     ) {
         use InferenceTypePart as ITP;
         let literal = &ctx.heap[lit_id];
         let extra_data_idx = self.expr_types[literal.unique_id_in_definition as usize].extra_data_idx; // TODO: @Temp
         debug_assert!(extra_data_idx != -1, "initial union polymorph data, but no preallocated ExtraData");
         let literal = ctx.heap[lit_id].value.as_union();
         // Construct the polymorphic variables
         let num_poly_args = literal.parser_type.elements[0].variant.num_embedded();
         let mut total_num_poly_parts = 0;
         let mut poly_args = Vec::with_capacity(num_poly_args);
         for embedded_elements in literal.parser_type.iter_embedded(0) {
             let poly_type = self.determine_inference_type_from_parser_type_elements(embedded_elements, true);
             total_num_poly_parts += poly_type.parts.len();
             poly_args.push(poly_type);
+        }
         // Handle any of the embedded values in the variant, if specified
         let definition_id = literal.definition;
         let type_definition = ctx.types.get_base_definition(&definition_id).unwrap();
         let union_definition = type_definition.definition.as_union();
         debug_assert_eq!(poly_args.len(), type_definition.poly_vars.len());
         let variant_definition = &union_definition.variants[literal.variant_idx];
         debug_assert_eq!(variant_definition.embedded.len(), literal.values.len());
         let mut embedded = Vec::with_capacity(variant_definition.embedded.len());
         for embedded_parser_type in &variant_definition.embedded {
             let inference_type = self.determine_inference_type_from_parser_type_elements(&embedded_parser_type.elements, false);
             embedded.push(inference_type);
+        }
         // Handle the type of the union itself
         let parts_reserved = 1 + poly_args.len() + total_num_poly_parts;
         let mut parts = Vec::with_capacity(parts_reserved);
         parts.push(ITP::Instance(definition_id, poly_args.len() as u32));
         let mut union_type_done = true;
         for (poly_var_idx, poly_var) in poly_args.iter().enumerate() {
             if !poly_var.is_done { union_type_done = false; }
             parts.push(ITP::Marker(poly_var_idx as u32));
             parts.extend(poly_var.parts.iter().cloned());
+        }
         debug_assert_eq!(parts_reserved, parts.len());
         let union_type = InferenceType::new(!poly_args.is_empty(), union_type_done, parts);
         self.extra_data[extra_data_idx as usize] = ExtraData{
             expr_id: lit_id.upcast(),
             definition_id: literal.definition,
             poly_vars: poly_args,
             embedded,
             returned: union_type
         };
+    }
     /// Inserts the extra polymorphic data struct. Assumes that the select
     /// expression's referenced (definition_id, field_idx) has been resolved.
     fn insert_initial_select_polymorph_data(
         &mut self, ctx: &Ctx, select_id: SelectExpressionId, struct_def_id: DefinitionId
     ) {
         use InferenceTypePart as ITP;
         // Retrieve relevant data
         let expr = &ctx.heap[select_id];
         let expr_type = &self.expr_types[expr.unique_id_in_definition as usize];
         let field_idx = expr_type.field_or_monomorph_idx as usize;
         let extra_data_idx = expr_type.extra_data_idx; // TODO: @Temp
         debug_assert!(extra_data_idx != -1, "initial select polymorph data, but no preallocated ExtraData");
         let definition = ctx.heap[struct_def_id].as_struct();
         // Generate initial polyvar types and struct type
         // TODO: @Performance: we can immediately set the polyvars of the subject's struct type
         let num_poly_vars = definition.poly_vars.len();
         let mut poly_vars = Vec::with_capacity(num_poly_vars);
         let struct_parts_reserved = 1 + 2 * num_poly_vars;
         let mut struct_parts = Vec::with_capacity(struct_parts_reserved);
         struct_parts.push(ITP::Instance(struct_def_id, num_poly_vars as u32));
         for poly_idx in 0..num_poly_vars {
             poly_vars.push(InferenceType::new(true, false, vec![
                 ITP::Marker(poly_idx as u32), ITP::Unknown,
             ]));
             struct_parts.push(ITP::Marker(poly_idx as u32));
             struct_parts.push(ITP::Unknown);
+        }
         debug_assert_eq!(struct_parts.len(), struct_parts_reserved);
         // Generate initial field type
         let field_type = self.determine_inference_type_from_parser_type_elements(&definition.fields[field_idx].parser_type.elements, false);
         self.extra_data[extra_data_idx as usize] = ExtraData{
             expr_id: select_id.upcast(),
             definition_id: struct_def_id,
             poly_vars,
             embedded: vec![InferenceType::new(num_poly_vars != 0, num_poly_vars == 0, struct_parts)],
             returned: field_type
         };
+    }
     /// Determines the initial InferenceType from the provided ParserType. This
     /// may be called with two kinds of intentions:
     /// 1. To resolve a ParserType within the body of a function, or on
     ///     polymorphic arguments to calls/instantiations within that body. This
     ///     means that the polymorphic variables are known and can be replaced
     ///     with the monomorph we're instantiating.
     /// 2. To resolve a ParserType on a called function's definition or on
     ///     an instantiated datatype's members. This means that the polymorphic
     ///     arguments inside those ParserTypes refer to the polymorphic
     ///     variables in the called/instantiated type's definition.
     /// In the second case we place InferenceTypePart::Marker instances such
     /// that we can perform type inference on the polymorphic variables.
     fn determine_inference_type_from_parser_type_elements(
         &mut self, elements: &[ParserTypeElement],
         use_definitions_known_poly_args: bool
     ) -> InferenceType {
         use ParserTypeVariant as PTV;
         use InferenceTypePart as ITP;
         let mut infer_type = Vec::with_capacity(elements.len());
         let mut has_inferred = false;
         let mut has_markers = false;
         for element in elements {
             match &element.variant {
                 // Compiler-only types
                 PTV::Void => { infer_type.push(ITP::Void); },
                 PTV::InputOrOutput => { infer_type.push(ITP::PortLike); has_inferred = true },
                 PTV::ArrayLike => { infer_type.push(ITP::ArrayLike); has_inferred = true },
                 PTV::IntegerLike => { infer_type.push(ITP::IntegerLike); has_inferred = true },
                 // Builtins
                 PTV::Message => {
                     // TODO: @types Remove the Message -> Byte hack at some point...
                     infer_type.push(ITP::Message);
                     infer_type.push(ITP::UInt8);
                 },
                 PTV::Bool => { infer_type.push(ITP::Bool); },
                 PTV::UInt8 => { infer_type.push(ITP::UInt8); },
                 PTV::UInt16 => { infer_type.push(ITP::UInt16); },
                 PTV::UInt32 => { infer_type.push(ITP::UInt32); },
                 PTV::UInt64 => { infer_type.push(ITP::UInt64); },
                 PTV::SInt8 => { infer_type.push(ITP::SInt8); },
                 PTV::SInt16 => { infer_type.push(ITP::SInt16); },
                 PTV::SInt32 => { infer_type.push(ITP::SInt32); },
                 PTV::SInt64 => { infer_type.push(ITP::SInt64); },
                 PTV::Character => { infer_type.push(ITP::Character); },
                 PTV::String => {
                     infer_type.push(ITP::String);
                     infer_type.push(ITP::Character);
                 },
                 // Special markers
                 PTV::IntegerLiteral => { unreachable!("integer literal type on variable type"); },
                 PTV::Inferred => {
                     infer_type.push(ITP::Unknown);
                     has_inferred = true;
                 },
                 // With nested types
                 PTV::Array => { infer_type.push(ITP::Array); },
                 PTV::Input => { infer_type.push(ITP::Input); },
                 PTV::Output => { infer_type.push(ITP::Output); },
                 PTV::Tuple(num_embedded) => { infer_type.push(ITP::Tuple(*num_embedded)); },
                 PTV::PolymorphicArgument(belongs_to_definition, poly_arg_idx) => {
                     let poly_arg_idx = *poly_arg_idx;
                     if use_definitions_known_poly_args {
                         // Refers to polymorphic argument on procedure we're currently processing.
                         // This argument is already known.
                         debug_assert_eq!(*belongs_to_definition, self.definition_type.definition_id());
                         debug_assert!((poly_arg_idx as usize) < self.poly_vars.len());
                         Self::determine_inference_type_from_concrete_type(
                             &mut infer_type, &self.poly_vars[poly_arg_idx as usize].parts
                         );
                     } else {
                         // Polymorphic argument has to be inferred
                         has_markers = true;
                         has_inferred = true;
                         infer_type.push(ITP::Marker(poly_arg_idx));
                         infer_type.push(ITP::Unknown)
+                    }
                 },
                 PTV::Definition(definition_id, num_embedded) => {
                     infer_type.push(ITP::Instance(*definition_id, *num_embedded));
+                }
+            }
+        }
         InferenceType::new(has_markers, !has_inferred, infer_type)
+    }
     /// Determines the inference type from an already concrete type. Applies the
     /// various type "hacks" inside the type inferencer.
     fn determine_inference_type_from_concrete_type(parser_type: &mut Vec<InferenceTypePart>, concrete_type: &[ConcreteTypePart]) {
         use InferenceTypePart as ITP;
         use ConcreteTypePart as CTP;
         for concrete_part in concrete_type {
             match concrete_part {
                 CTP::Void => parser_type.push(ITP::Void),
                 CTP::Message => {
                     parser_type.push(ITP::Message);
                     parser_type.push(ITP::UInt8)
                 },
                 CTP::Bool => parser_type.push(ITP::Bool),
                 CTP::UInt8 => parser_type.push(ITP::UInt8),
                 CTP::UInt16 => parser_type.push(ITP::UInt16),
                 CTP::UInt32 => parser_type.push(ITP::UInt32),
                 CTP::UInt64 => parser_type.push(ITP::UInt64),
                 CTP::SInt8 => parser_type.push(ITP::SInt8),
                 CTP::SInt16 => parser_type.push(ITP::SInt16),
                 CTP::SInt32 => parser_type.push(ITP::SInt32),
                 CTP::SInt64 => parser_type.push(ITP::SInt64),
                 CTP::Character => parser_type.push(ITP::Character),
                 CTP::String => {
                     parser_type.push(ITP::String);
                     parser_type.push(ITP::Character)
                 },
                 CTP::Array => parser_type.push(ITP::Array),
                 CTP::Slice => parser_type.push(ITP::Slice),
                 CTP::Input => parser_type.push(ITP::Input),
                 CTP::Output => parser_type.push(ITP::Output),
                 CTP::Tuple(num) => parser_type.push(ITP::Tuple(*num)),
                 CTP::Instance(id, num) => parser_type.push(ITP::Instance(*id, *num)),
                 CTP::Function(_, _) => unreachable!("function type during concrete to inference type conversion"),
                 CTP::Component(_, _) => unreachable!("component type during concrete to inference type conversion"),
+            }
+        }
+    }
     /// Construct an error when an expression's type does not match. This
     /// happens if we infer the expression type from its arguments (e.g. the
     /// expression type of an addition operator is the type of the arguments)
     /// But the expression type was already set due to our parent (e.g. an
     /// "if statement" or a "logical not" always expecting a boolean)
     fn construct_expr_type_error(
         &self, ctx: &Ctx, expr_id: ExpressionId, arg_id: ExpressionId
     ) -> ParseError {
         // TODO: Expand and provide more meaningful information for humans
         let expr = &ctx.heap[expr_id];
         let arg_expr = &ctx.heap[arg_id];
         let expr_idx = expr.get_unique_id_in_definition();
         let arg_expr_idx = arg_expr.get_unique_id_in_definition();
         let expr_type = &self.expr_types[expr_idx as usize].expr_type;
         let arg_type = &self.expr_types[arg_expr_idx as usize].expr_type;
         return ParseError::new_error_at_span(
             &ctx.module().source, expr.operation_span(), format!(
                 "incompatible types: this expression expected a '{}'",
                 expr_type.display_name(&ctx.heap)
+            )
         ).with_info_at_span(
             &ctx.module().source, arg_expr.full_span(), format!(
                 "but this expression yields a '{}'",
                 arg_type.display_name(&ctx.heap)
+            )
+        )
+    }
     fn construct_arg_type_error(
         &self, ctx: &Ctx, expr_id: ExpressionId,
         arg1_id: ExpressionId, arg2_id: ExpressionId
     ) -> ParseError {
         let expr = &ctx.heap[expr_id];
         let arg1 = &ctx.heap[arg1_id];
         let arg2 = &ctx.heap[arg2_id];
         let arg1_idx = arg1.get_unique_id_in_definition();
         let arg1_type = &self.expr_types[arg1_idx as usize].expr_type;
         let arg2_idx = arg2.get_unique_id_in_definition();
         let arg2_type = &self.expr_types[arg2_idx as usize].expr_type;
         return ParseError::new_error_str_at_span(
             &ctx.module().source, expr.operation_span(),
             "incompatible types: cannot apply this expression"
         ).with_info_at_span(
             &ctx.module().source, arg1.full_span(), format!(
                 "Because this expression has type '{}'",
                 arg1_type.display_name(&ctx.heap)
+            )
         ).with_info_at_span(
             &ctx.module().source, arg2.full_span(), format!(
                 "But this expression has type '{}'",
                 arg2_type.display_name(&ctx.heap)
+            )
+        )
+    }
     fn construct_template_type_error(
         &self, ctx: &Ctx, expr_id: ExpressionId, template: &[InferenceTypePart]
     ) -> ParseError {
         let expr = &ctx.heap[expr_id];
         let expr_idx = expr.get_unique_id_in_definition();
         let expr_type = &self.expr_types[expr_idx as usize].expr_type;
         return ParseError::new_error_at_span(
             &ctx.module().source, expr.full_span(), format!(
                 "incompatible types: got a '{}' but expected a '{}'",
                 expr_type.display_name(&ctx.heap),
                 InferenceType::partial_display_name(&ctx.heap, template)
+            )
+        )
+    }
     /// Constructs a human interpretable error in the case that type inference
     /// on a polymorphic variable to a function call or literal construction
     /// failed. This may only be caused by a pair of inference types (which may
     /// come from arguments or the return type) having two different inferred
     /// values for that polymorphic variable.
     ///
     /// So we find this pair and construct the error using it.
     ///
     /// We assume that the expression is a function call or a struct literal,
     /// and that an actual error has occurred.
     fn construct_poly_arg_error(
         ctx: &Ctx, poly_data: &ExtraData, expr_id: ExpressionId
     ) -> ParseError {
         // Helper function to check for polymorph mismatch between two inference
         // types.
         fn has_poly_mismatch<'a>(type_a: &'a InferenceType, type_b: &'a InferenceType) -> Option<(u32, &'a [InferenceTypePart], &'a [InferenceTypePart])> {
             if !type_a.has_marker || !type_b.has_marker {
                 return None
+            }
             for (marker_a, section_a) in type_a.marker_iter() {
                 for (marker_b, section_b) in type_b.marker_iter() {
                     if marker_a != marker_b {
                         // Not the same polymorphic variable
                         continue;
+                    }
                     if !InferenceType::check_subtrees(section_a, 0, section_b, 0) {
                         // Not compatible
                         return Some((marker_a, section_a, section_b))
+                    }
+                }
+            }
             None
+        }
         // Helper function to check for polymorph mismatch between an inference
         // type and the polymorphic variables in the poly_data struct.
         fn has_explicit_poly_mismatch<'a>(
             poly_vars: &'a [InferenceType], arg: &'a InferenceType
         ) -> Option<(u32, &'a [InferenceTypePart], &'a [InferenceTypePart])> {
             for (marker, section) in arg.marker_iter() {
                 debug_assert!((marker as usize) < poly_vars.len());
                 let poly_section = &poly_vars[marker as usize].parts;
                 if !InferenceType::check_subtrees(poly_section, 0, section, 0) {
                     return Some((marker, poly_section, section))
+                }
+            }
             None
+        }
         // Helpers function to retrieve polyvar name and definition name
         fn get_poly_var_and_definition_name<'a>(ctx: &'a Ctx, poly_var_idx: u32, definition_id: DefinitionId) -> (&'a str, &'a str) {
             let definition = &ctx.heap[definition_id];
             let poly_var = definition.poly_vars()[poly_var_idx as usize].value.as_str();
             let func_name = definition.identifier().value.as_str();
             (poly_var, func_name)
+        }
         // Helper function to construct initial error
         fn construct_main_error(ctx: &Ctx, poly_data: &ExtraData, poly_var_idx: u32, expr: &Expression) -> ParseError {
             match expr {
                 Expression::Call(expr) => {
                     let (poly_var, func_name) = get_poly_var_and_definition_name(ctx, poly_var_idx, poly_data.definition_id);
                     return ParseError::new_error_at_span(
                         &ctx.module().source, expr.func_span, format!(
                             "Conflicting type for polymorphic variable '{}' of '{}'",
                             poly_var, func_name
+                        )
+                    )
                 },
                 Expression::Literal(expr) => {
                     let (poly_var, type_name) = get_poly_var_and_definition_name(ctx, poly_var_idx, poly_data.definition_id);
                     return ParseError::new_error_at_span(
                         &ctx.module().source, expr.span, format!(
                             "Conflicting type for polymorphic variable '{}' of instantiation of '{}'",
                             poly_var, type_name
+                        )
                     );
                 },
                 Expression::Select(expr) => {
                     let (poly_var, struct_name) = get_poly_var_and_definition_name(ctx, poly_var_idx, poly_data.definition_id);
                     return ParseError::new_error_at_span(
                         &ctx.module().source, expr.full_span, format!(
                             "Conflicting type for polymorphic variable '{}' while accessing field '{}' of '{}'",
                             poly_var, expr.field_name.value.as_str(), struct_name
+                        )
+                    )
+                }
                 _ => unreachable!("called construct_poly_arg_error without an expected expression, got: {:?}", expr)
+            }
+        }
         // Actual checking
         let expr = &ctx.heap[expr_id];
         let (expr_args, expr_return_name) = match expr {
             Expression::Call(expr) =>
+                (
                     expr.arguments.clone(),
                     "return type"
                 ),
             Expression::Literal(expr) => {
                 let expressions = match &expr.value {
                     Literal::Struct(v) => v.fields.iter()
                         .map(|f| f.value)
                         .collect(),
                     Literal::Enum(_) => Vec::new(),
                     Literal::Union(v) => v.values.clone(),
                     _ => unreachable!()
                 };
                 ( expressions, "literal" )
             },
             Expression::Select(expr) =>
                 // Select expression uses the polymorphic variables of the
                 // struct it is accessing, so get the subject expression.
+                (
                     vec![expr.subject],
                     "selected field"
                 ),
             _ => unreachable!(),
         };
         // - check return type with itself
         if let Some((poly_idx, section_a, section_b)) = has_poly_mismatch(
             &poly_data.returned, &poly_data.returned
         ) {
             return construct_main_error(ctx, poly_data, poly_idx, expr)
                 .with_info_at_span(
                     &ctx.module().source, expr.full_span(), format!(
                         "The {} inferred the conflicting types '{}' and '{}'",
                         expr_return_name,
                         InferenceType::partial_display_name(&ctx.heap, section_a),
                         InferenceType::partial_display_name(&ctx.heap, section_b)
+                    )
                 );
+        }
         // - check arguments with each other argument and with return type
         for (arg_a_idx, arg_a) in poly_data.embedded.iter().enumerate() {
             for (arg_b_idx, arg_b) in poly_data.embedded.iter().enumerate() {
                 if arg_b_idx > arg_a_idx {
                     break;
+                }
                 if let Some((poly_idx, section_a, section_b)) = has_poly_mismatch(&arg_a, &arg_b) {
                     let error = construct_main_error(ctx, poly_data, poly_idx, expr);
                     if arg_a_idx == arg_b_idx {
                         // Same argument
                         let arg = &ctx.heap[expr_args[arg_a_idx]];
                         return error.with_info_at_span(
                             &ctx.module().source, arg.full_span(), format!(
                                 "This argument inferred the conflicting types '{}' and '{}'",
                                 InferenceType::partial_display_name(&ctx.heap, section_a),
                                 InferenceType::partial_display_name(&ctx.heap, section_b)
+                            )
                         );
                     } else {
                         let arg_a = &ctx.heap[expr_args[arg_a_idx]];
                         let arg_b = &ctx.heap[expr_args[arg_b_idx]];
                         return error.with_info_at_span(
                             &ctx.module().source, arg_a.full_span(), format!(
                                 "This argument inferred it to '{}'",
                                 InferenceType::partial_display_name(&ctx.heap, section_a)
+                            )
                         ).with_info_at_span(
                             &ctx.module().source, arg_b.full_span(), format!(
                                 "While this argument inferred it to '{}'",
                                 InferenceType::partial_display_name(&ctx.heap, section_b)
+                            )
+                        )
+                    }
+                }
+            }
             // Check with return type
             if let Some((poly_idx, section_arg, section_ret)) = has_poly_mismatch(arg_a, &poly_data.returned) {
                 let arg = &ctx.heap[expr_args[arg_a_idx]];
                 return construct_main_error(ctx, poly_data, poly_idx, expr)
                     .with_info_at_span(
                         &ctx.module().source, arg.full_span(), format!(
                             "This argument inferred it to '{}'",
                             InferenceType::partial_display_name(&ctx.heap, section_arg)
+                        )
+                    )
                     .with_info_at_span(
                         &ctx.module().source, expr.full_span(), format!(
                             "While the {} inferred it to '{}'",
                             expr_return_name,
                             InferenceType::partial_display_name(&ctx.heap, section_ret)
+                        )
                     );
+            }
+        }
         // Now check against the explicitly specified polymorphic variables (if
         // any).
         for (arg_idx, arg) in poly_data.embedded.iter().enumerate() {
             if let Some((poly_idx, poly_section, arg_section)) = has_explicit_poly_mismatch(&poly_data.poly_vars, arg) {
                 let arg = &ctx.heap[expr_args[arg_idx]];
                 return construct_main_error(ctx, poly_data, poly_idx, expr)
                     .with_info_at_span(
                         &ctx.module().source, arg.full_span(), format!(
                             "The polymorphic variable has type '{}' (which might have been partially inferred) while the argument inferred it to '{}'",
                             InferenceType::partial_display_name(&ctx.heap, poly_section),
                             InferenceType::partial_display_name(&ctx.heap, arg_section)
+                        )
                     );
+            }
+        }
         if let Some((poly_idx, poly_section, ret_section)) = has_explicit_poly_mismatch(&poly_data.poly_vars, &poly_data.returned) {
             return construct_main_error(ctx, poly_data, poly_idx, expr)
                 .with_info_at_span(
                     &ctx.module().source, expr.full_span(), format!(
                         "The polymorphic variable has type '{}' (which might have been partially inferred) while the {} inferred it to '{}'",
                         InferenceType::partial_display_name(&ctx.heap, poly_section),
                         expr_return_name,
                         InferenceType::partial_display_name(&ctx.heap, ret_section)
+                    )
+                )
+        }
         unreachable!("construct_poly_arg_error without actual error found?")
+    }
+}
 #[cfg(test)]
 mod tests {
     use super::*;
     use crate::protocol::arena::Id;
     use InferenceTypePart as ITP;
     use InferenceType as IT;
     #[test]
     fn test_single_part_inference() {
         // lhs argument inferred from rhs
         let pairs = [
             (ITP::NumberLike, ITP::UInt8),
             (ITP::IntegerLike, ITP::SInt32),
             (ITP::Unknown, ITP::UInt64),
             (ITP::Unknown, ITP::Bool)
         ];
         for (lhs, rhs) in pairs.iter() {
             // Using infer-both
             let mut lhs_type = IT::new(false, false, vec![lhs.clone()]);
             let mut rhs_type = IT::new(false, true, vec![rhs.clone()]);
             let result = unsafe{ IT::infer_subtrees_for_both_types(
                 &mut lhs_type, 0, &mut rhs_type, 0
             ) };
             assert_eq!(DualInferenceResult::First, result);
             assert_eq!(lhs_type.parts, rhs_type.parts);
             // Using infer-single
             let mut lhs_type = IT::new(false, false, vec![lhs.clone()]);
             let rhs_type = IT::new(false, true, vec![rhs.clone()]);
             let result = IT::infer_subtree_for_single_type(
                 &mut lhs_type, 0, &rhs_type.parts, 0, false
             );
             assert_eq!(SingleInferenceResult::Modified, result);
             assert_eq!(lhs_type.parts, rhs_type.parts);
+        }
+    }
     #[test]
     fn test_multi_part_inference() {
         let pairs = [
             (vec![ITP::ArrayLike, ITP::NumberLike], vec![ITP::Slice, ITP::SInt8]),
             (vec![ITP::Unknown], vec![ITP::Input, ITP::Array, ITP::String, ITP::Character]),
             (vec![ITP::PortLike, ITP::SInt32], vec![ITP::Input, ITP::SInt32]),
             (vec![ITP::Unknown], vec![ITP::Output, ITP::SInt32]),
+            (
                 vec![ITP::Instance(Id::new(0), 2), ITP::Input, ITP::Unknown, ITP::Output, ITP::Unknown],
                 vec![ITP::Instance(Id::new(0), 2), ITP::Input, ITP::Array, ITP::SInt32, ITP::Output, ITP::SInt32]
+            )
         ];
         for (lhs, rhs) in pairs.iter() {
             let mut lhs_type = IT::new(false, false, lhs.clone());
             let mut rhs_type = IT::new(false, true, rhs.clone());
             let result = unsafe{ IT::infer_subtrees_for_both_types(
                 &mut lhs_type, 0, &mut rhs_type, 0
             ) };
             assert_eq!(DualInferenceResult::First, result);
             assert_eq!(lhs_type.parts, rhs_type.parts);
             let mut lhs_type = IT::new(false, false, lhs.clone());
             let rhs_type = IT::new(false, true, rhs.clone());
             let result = IT::infer_subtree_for_single_type(
                 &mut lhs_type, 0, &rhs_type.parts, 0, false
             );
             assert_eq!(SingleInferenceResult::Modified, result);
             assert_eq!(lhs_type.parts, rhs_type.parts)
+        }
+    }
+}
@@ \ No newline at end of file @@

src/protocol/parser/type_table.rs

➞

Show inline comments

 /**
  * type_table.rs
+ *
  * The type table is a lookup from AST definition (which contains just what the
  * programmer typed) to a type with additional information computed (e.g. the
  * byte size and offsets of struct members). The type table should be considered
  * the authoritative source of information on types by the compiler (not the
  * AST itself!).
+ *
  * The type table operates in two modes: one is where we just look up the type,
  * check its fields for correctness and mark whether it is polymorphic or not.
  * The second one is where we compute byte sizes, alignment and offsets.
+ *
  * The basic algorithm for type resolving and computing byte sizes is to
  * recursively try to lay out each member type of a particular type. This is
  * done in a stack-like fashion, where each embedded type pushes a breadcrumb
  * unto the stack. We may discover a cycle in embedded types (we call this a
  * "type loop"). After which the type table attempts to break the type loop by
  * making specific types heap-allocated. Upon doing so we know their size
  * because their stack-size is now based on pointers. Hence breaking the type
  * loop required for computing the byte size of types.
+ *
  * The reason for these type shenanigans is because PDL is a value-based
  * language, but we would still like to be able to express recursively defined
  * types like trees or linked lists. Hence we need to insert pointers somewhere
  * to break these cycles.
+ *
  * We will insert these pointers into the variants of unions. However note that
  * we can only compute the stack size of a union until we've looked at *all*
  * variants. Hence we perform an initial pass where we detect type loops, a
  * second pass where we compute the stack sizes of everything, and a third pass
  * where we actually compute the size of the heap allocations for unions.
+ *
  * As a final bit of global documentation: non-polymorphic types will always
  * have one "monomorph" entry. This contains the non-polymorphic type's memory
  * layout.
  */
 use std::fmt::{Formatter, Result as FmtResult};
 use std::collections::HashMap;
 use crate::protocol::ast::*;
 use crate::protocol::parser::symbol_table::SymbolScope;
 use crate::protocol::input_source::ParseError;
 use crate::protocol::parser::*;
 //------------------------------------------------------------------------------
 // Defined Types
 //------------------------------------------------------------------------------
 #[derive(Copy, Clone, PartialEq, Eq)]
 pub enum TypeClass {
     Enum,
     Union,
     Struct,
     Function,
     Component
+}
 impl TypeClass {
     pub(crate) fn display_name(&self) -> &'static str {
         match self {
             TypeClass::Enum => "enum",
             TypeClass::Union => "union",
             TypeClass::Struct => "struct",
             TypeClass::Function => "function",
             TypeClass::Component => "component",
+        }
+    }
     pub(crate) fn is_data_type(&self) -> bool {
         match self {
             TypeClass::Enum | TypeClass::Union | TypeClass::Struct => true,
             TypeClass::Function | TypeClass::Component => false,
+        }
+    }
+}
 impl std::fmt::Display for TypeClass {
     fn fmt(&self, f: &mut Formatter<'_>) -> FmtResult {
         write!(f, "{}", self.display_name())
+    }
+}
 /// Struct wrapping around a potentially polymorphic type. If the type does not
 /// have any polymorphic arguments then it will not have any monomorphs and
 /// `is_polymorph` will be set to `false`. A type with polymorphic arguments
 /// only has `is_polymorph` set to `true` if the polymorphic arguments actually
 /// appear in the types associated types (function return argument, struct
 /// field, enum variant, etc.). Otherwise the polymorphic argument is just a
 /// marker and does not influence the bytesize of the type.
 pub struct DefinedType {
     pub(crate) ast_root: RootId,
     pub(crate) ast_definition: DefinitionId,
     pub(crate) definition: DefinedTypeVariant,
     pub(crate) poly_vars: Vec<PolymorphicVariable>,
     pub(crate) is_polymorph: bool,
+}
 impl DefinedType {
     /// Returns the number of monomorphs that are instantiated. Remember that
     /// during the type loop detection, and the memory layout phase we will
     /// pre-allocate monomorphs which are not yet fully laid out in memory.
     pub(crate) fn num_monomorphs(&self) -> usize {
         use DefinedTypeVariant as DTV;
         match &self.definition {
             DTV::Enum(def) => def.monomorphs.len(),
             DTV::Union(def) => def.monomorphs.len(),
             DTV::Struct(def) => def.monomorphs.len(),
             DTV::Function(_) | DTV::Component(_) => unreachable!(),
+        }
+    }
     /// Returns the index at which a monomorph occurs. Will only check the
     /// polymorphic arguments that are in use (none of the, in rust lingo,
     /// phantom types). If the type is not polymorphic and its memory has been
     /// layed out, then this will always return `Some(0)`.
     pub(crate) fn get_monomorph_index(&self, parts: &[ConcreteTypePart]) -> Option<usize> {
         use DefinedTypeVariant as DTV;
         // Helper to compare two types, while disregarding the polymorphic
         // variables that are not in use.
         let concrete_types_match = |type_a: &[ConcreteTypePart], type_b: &[ConcreteTypePart], check_if_poly_var_is_used: bool| -> bool {
             let mut a_iter = ConcreteTypeIter::new(type_a, 0).enumerate();
             let mut b_iter = ConcreteTypeIter::new(type_b, 0);
             while let Some((section_idx, a_section)) = a_iter.next() {
                 let b_section = b_iter.next().unwrap();
                 if check_if_poly_var_is_used && !self.poly_vars[section_idx].is_in_use {
                     continue;
+                }
                 if a_section != b_section {
                     return false;
+                }
+            }
             return true;
         };
         // Check check if type is polymorphic to some degree at all
         if cfg!(debug_assertions) {
             if let ConcreteTypePart::Instance(definition_id, num_poly_args) = parts[0] {
                 assert_eq!(definition_id, self.ast_definition);
                 assert_eq!(num_poly_args as usize, self.poly_vars.len());
             } else {
                 assert!(false, "concrete type {:?} is not a user-defined type", parts);
+            }
+        }
         match &self.definition {
             DTV::Enum(definition) => {
                 // Special case, enum is never a "true polymorph"
                 debug_assert!(!self.is_polymorph);
                 if definition.monomorphs.is_empty() {
                     return None
                 } else {
                     return Some(0)
+                }
             },
             DTV::Union(definition) => {
                 for (monomorph_idx, monomorph) in definition.monomorphs.iter().enumerate() {
                     if concrete_types_match(&monomorph.concrete_type.parts, parts, true) {
                         return Some(monomorph_idx);
+                    }
+                }
             },
             DTV::Struct(definition) => {
                 for (monomorph_idx, monomorph) in definition.monomorphs.iter().enumerate() {
                     if concrete_types_match(&monomorph.concrete_type.parts, parts, true) {
                         return Some(monomorph_idx);
+                    }
+                }
             },
             DTV::Function(definition) => {
                 for (monomorph_idx, monomorph) in definition.monomorphs.iter().enumerate() {
                     if concrete_types_match(&monomorph.concrete_type.parts, parts, false) {
                         return Some(monomorph_idx)
+                    }
+                }
+            }
             DTV::Component(definition) => {
                 for (monomorph_idx, monomorph) in definition.monomorphs.iter().enumerate() {
                     if concrete_types_match(&monomorph.concrete_type.parts, parts, false) {
                         return Some(monomorph_idx)
+                    }
+                }
+            }
+        }
         // Nothing matched
         return None;
+    }
     /// Retrieves size and alignment of the particular type's monomorph if it
     /// has been layed out in memory.
     pub(crate) fn get_monomorph_size_alignment(&self, idx: usize) -> Option<(usize, usize)> {
         use DefinedTypeVariant as DTV;
         let (size, alignment) = match &self.definition {
             DTV::Enum(def) => {
                 debug_assert!(idx == 0);
                 (def.size, def.alignment)
             },
             DTV::Union(def) => {
                 let monomorph = &def.monomorphs[idx];
                 (monomorph.stack_size, monomorph.stack_alignment)
             },
             DTV::Struct(def) => {
                 let monomorph = &def.monomorphs[idx];
                 (monomorph.size, monomorph.alignment)
             },
             DTV::Function(_) | DTV::Component(_) => {
                 // Type table should never be able to arrive here during layout
                 // of types. Types may only contain function prototypes.
                 unreachable!("retrieving size and alignment of procedure type");
+            }
         };
         if size == 0 && alignment == 0 {
             // The "marker" for when the type has not been layed out yet. Even
             // for zero-size types we will set alignment to `1` to simplify
             // alignment calculations.
             return None;
         } else {
             return Some((size, alignment));
+        }
+    }
+}
 pub enum DefinedTypeVariant {
     Enum(EnumType),
     Union(UnionType),
     Struct(StructType),
     Function(FunctionType),
     Component(ComponentType)
+}
 impl DefinedTypeVariant {
     pub(crate) fn type_class(&self) -> TypeClass {
         match self {
             DefinedTypeVariant::Enum(_) => TypeClass::Enum,
             DefinedTypeVariant::Union(_) => TypeClass::Union,
             DefinedTypeVariant::Struct(_) => TypeClass::Struct,
             DefinedTypeVariant::Function(_) => TypeClass::Function,
             DefinedTypeVariant::Component(_) => TypeClass::Component
+        }
+    }
     pub(crate) fn as_struct(&self) -> &StructType {
         match self {
             DefinedTypeVariant::Struct(v) => v,
             _ => unreachable!("Cannot convert {} to struct variant", self.type_class())
+        }
+    }
     pub(crate) fn as_struct_mut(&mut self) -> &mut StructType {
         match self {
             DefinedTypeVariant::Struct(v) => v,
             _ => unreachable!("Cannot convert {} to struct variant", self.type_class())
+        }
+    }
     pub(crate) fn as_enum(&self) -> &EnumType {
         match self {
             DefinedTypeVariant::Enum(v) => v,
             _ => unreachable!("Cannot convert {} to enum variant", self.type_class())
+        }
+    }
     pub(crate) fn as_enum_mut(&mut self) -> &mut EnumType {
         match self {
             DefinedTypeVariant::Enum(v) => v,
             _ => unreachable!("Cannot convert {} to enum variant", self.type_class())
+        }
+    }
     pub(crate) fn as_union(&self) -> &UnionType {
         match self {
             DefinedTypeVariant::Union(v) => v,
             _ => unreachable!("Cannot convert {} to union variant", self.type_class())
+        }
+    }
     pub(crate) fn as_union_mut(&mut self) -> &mut UnionType {
         match self {
             DefinedTypeVariant::Union(v) => v,
             _ => unreachable!("Cannot convert {} to union variant", self.type_class())
+        }
+    }
     pub(crate) fn procedure_monomorphs(&self) -> &Vec<ProcedureMonomorph> {
         use DefinedTypeVariant::*;
         match self {
             Function(v) => &v.monomorphs,
             Component(v) => &v.monomorphs,
             _ => unreachable!("cannot get procedure monomorphs from {}", self.type_class()),
+        }
+    }
     pub(crate) fn procedure_monomorphs_mut(&mut self) -> &mut Vec<ProcedureMonomorph> {
         use DefinedTypeVariant::*;
         match self {
             Function(v) => &mut v.monomorphs,
             Component(v) => &mut v.monomorphs,
             _ => unreachable!("cannot get procedure monomorphs from {}", self.type_class()),
+        }
+    }
+}
 pub struct PolymorphicVariable {
     identifier: Identifier,
     is_in_use: bool, // a polymorphic argument may be defined, but not used by the type definition
+}
 /// `EnumType` is the classical C/C++ enum type. It has various variants with
 /// an assigned integer value. The integer values may be user-defined,
 /// compiler-defined, or a mix of the two. If a user assigns the same enum
 /// value multiple times, we assume the user is an expert and we consider both
 /// variants to be equal to one another.
 pub struct EnumType {
     pub variants: Vec<EnumVariant>,
     pub monomorphs: Vec<EnumMonomorph>,
     pub minimum_tag_value: i64,
     pub maximum_tag_value: i64,
     pub tag_type: ConcreteType,
     pub size: usize,
     pub alignment: usize,
+}
 // TODO: Also support maximum u64 value
 pub struct EnumVariant {
     pub identifier: Identifier,
     pub value: i64,
+}
 /// `UnionType` is the algebraic datatype (or sum type, or discriminated union).
 /// A value is an element of the union, identified by its tag, and may contain
 /// a single subtype.
 /// For potentially infinite types (i.e. a tree, or a linked list) only unions
 /// can break the infinite cycle. So when we lay out these unions in memory we
 /// will reserve enough space on the stack for all union variants that do not
 /// cause "type loops" (i.e. a union `A` with a variant containing a struct
 /// `B`). And we will reserve enough space on the heap (and store a pointer in
 /// the union) for all variants which do cause type loops (i.e. a union `A`
 /// with a variant to a struct `B` that contains the union `A` again).
 pub struct UnionType {
     pub variants: Vec<UnionVariant>,
     pub monomorphs: Vec<UnionMonomorph>,
     pub tag_type: ConcreteType,
     pub tag_size: usize,
+}
 pub struct UnionVariant {
     pub identifier: Identifier,
     pub embedded: Vec<ParserType>, // zero-length does not have embedded values
     pub tag_value: i64,
+}
 /// `StructType` is a generic C-like struct type (or record type, or product
 /// type) type.
 pub struct StructType {
     pub fields: Vec<StructField>,
     pub monomorphs: Vec<StructMonomorph>,
+}
 pub struct StructField {
     pub identifier: Identifier,
     pub parser_type: ParserType,
+}
 /// `FunctionType` is what you expect it to be: a particular function's
 /// signature.
 pub struct FunctionType {
     pub return_types: Vec<ParserType>,
     pub arguments: Vec<FunctionArgument>,
     pub monomorphs: Vec<ProcedureMonomorph>,
+}
 pub struct ComponentType {
     pub variant: ComponentVariant,
     pub arguments: Vec<FunctionArgument>,
     pub monomorphs: Vec<ProcedureMonomorph>
+}
 pub struct FunctionArgument {
     identifier: Identifier,
     parser_type: ParserType,
+}
 /// Represents the data associated with a single expression after type inference
 /// for a monomorph (or just the normal expression types, if dealing with a
 /// non-polymorphic function/component).
 pub struct MonomorphExpression {
     // The output type of the expression. Note that for a function it is not the
     // function's signature but its return type
     pub(crate) expr_type: ConcreteType,
     // Has multiple meanings: the field index for select expressions, the
     // monomorph index for polymorphic function calls or literals. Negative
     // values are never used, but used to catch programming errors.
     pub(crate) field_or_monomorph_idx: i32,
+}
 //------------------------------------------------------------------------------
 // Type monomorph storage
 //------------------------------------------------------------------------------
 /// Union of all possible type monomorphs. The term "monomorph" is perhaps not
 /// entirely correct: nonpolymorphic types will also get a "monomorph" entry to
 /// store the size/offset/alignment data of all types.
 enum TypeMonomorph {
     Enum(EnumMonomorph),
 /// Generic monomorph has a specific concrete type, a size and an alignment.
 /// Extra data is in the `MonomorphVariant` per kind of type.
 pub(crate) struct TypeMonomorph {
     pub concrete_type: ConcreteType,
     pub size: usize,
     pub alignment: usize,
     pub variant: MonomorphVariant,
+}
 pub(crate) enum MonomorphVariant {
     Enum, // no extra data
     Struct(StructMonomorph),
     Union(UnionMonomorph),
     Procedure(ProcedureMonomorph), // functions, components
     Tuple(TupleMonomorph),
+}
 /// Enum monomorph
 pub struct EnumMonomorph {
     pub concrete_type: ConcreteType,
     pub size: usize,
     pub alignment: usize,
 impl MonomorphVariant {
     fn as_struct(&self) -> &StructMonomorph {
         match self {
             MonomorphVariant::Struct(v) => v,
             _ => unreachable!(),
+        }
+    }
     fn as_struct_mut(&mut self) -> &mut StructMonomorph {
         match self {
             MonomorphVariant::Struct(v) => v,
             _ => unreachable!(),
+        }
+    }
     pub(crate) fn as_union(&self) -> &UnionMonomorph {
         match self {
             MonomorphVariant::Union(v) => v,
             _ => unreachable!(),
+        }
+    }
     fn as_union_mut(&mut self) -> &mut UnionMonomorph {
         match self {
             MonomorphVariant::Union(v) => v,
             _ => unreachable!(),
+        }
+    }
     fn as_tuple(&self) -> &TupleMonomorph {
         match self {
             MonomorphVariant::Tuple(v) => v,
             _ => unreachable!(),
+        }
+    }
     fn as_tuple_mut(&mut self) -> &mut TupleMonomorph {
         match self {
             MonomorphVariant::Tuple(v) => v,
             _ => unreachable!(),
+        }
+    }
     fn as_procedure(&self) -> &ProcedureMonomorph {
         match self {
             MonomorphVariant::Procedure(v) => v,
             _ => unreachable!(),
+        }
+    }
     fn as_procedure_mut(&mut self) -> &mut ProcedureMonomorph {
         match self {
             MonomorphVariant::Procedure(v) => v,
             _ => unreachable!(),
+        }
+    }
+}
 /// Struct monomorph
 pub struct StructMonomorph {
     pub concrete_type: ConcreteType,
     pub fields: Vec<StructMonomorphField>,
     pub size: usize,
     pub alignment: usize,
+}
 pub struct StructMonomorphField {
     pub concrete_type: ConcreteType,
     pub size: usize,
     pub alignment: usize,
     pub offset: usize,
+}
 /// Union monomorph
 pub struct UnionMonomorph {
     pub concrete_type: ConcreteType,
     pub variants: Vec<UnionMonomorphVariant>,
     // stack_size is the size of the union on the stack, includes the tag
     pub stack_size: usize,
     pub stack_alignment: usize,
     // note that the stack size is in the `TypeMonomorph` struct. This size and
     // alignment will include the size of the union tag.
     //
     // heap_size contains the allocated size of the union in the case it
     // is used to break a type loop. If it is 0, then it doesn't require
     // allocation and lives entirely on the stack.
     pub heap_size: usize,
     pub heap_alignment: usize,
+}
 pub struct UnionMonomorphVariant {
     pub lives_on_heap: bool,
     pub embedded: Vec<UnionMonomorphEmbedded>,
+}
 pub struct UnionMonomorphEmbedded {
     pub concrete_type: ConcreteType,
     // Note that the meaning of the offset (and alignment) depend on whether or
     // not the variant lives on the stack/heap. If it lives on the stack then
     // they refer to the offset from the start of the union value (so the first
     // embedded type lives at a non-zero offset, because the union tag sits in
     // the front). If it lives on the heap then it refers to the offset from the
     // allocated memory region (so the first embedded type lives at a 0 offset).
     pub size: usize,
     pub alignment: usize,
     pub offset: usize,
+}
 /// Procedure (functions and components of all possible types) monomorph. Also
 /// stores the expression type data from the typechecking/inferencing pass.
 pub struct ProcedureMonomorph {
     // Expression data for one particular monomorph
     pub concrete_type: ConcreteType,
     pub arg_types: Vec<ConcreteType>,
     pub expr_data: Vec<MonomorphExpression>,
+}
 /// Tuple monomorph. Again a kind of exception because one cannot define a named
 /// tuple type containing explicit polymorphic variables. But again: we need to
 /// store size/offset/alignment information, so we do it here.
 pub struct TupleMonomorph {
     pub concrete_type: ConcreteType,
     pub size: usize,
     pub alignment: usize,
     pub members: Vec<TupleMonomorphMember>
+}
 pub struct TupleMonomorphMember {
     pub concrete_type: ConcreteType,
     pub size: usize,
     pub alignment: usize,
     pub offset: usize,
+}
 /// Key used to perform lookups in the monomorph table. It computes a hash of
 /// the type while not taking the unused polymorphic variables of the base type
 /// into account (e.g. `struct Foo<A,B>{ A field }`, here `B` is an unused
 /// polymorphic variable).
 struct MonomorphKey {
     parts: Vec<ConcreteTypePart>,
     in_use: Vec<bool>,
+}
 use std::hash::*;
 impl Hash for MonomorphKey {
     fn hash<H: Hasher>(&self, state: &mut H) {
         // if `in_use` is empty, then we may assume the type is not polymorphic
         // (or all types are in use)
         if self.in_use.is_empty() {
             self.parts.hash(state);
         } else {
             // type is polymorphic
             self.parts[0].hash(state);
             // note: hash is computed in a unique way, because practically
             // speaking `in_use` is fixed per base type. So we cannot have the
             // same base type (hence: a type with the same DefinitionId) with
             // different different polymorphic variables in use.
             let mut in_use_index = 0;
             for section in ConcreteTypeIter::new(self.parts.as_slice(), 0) {
                 if self.in_use[in_use_index] {
                     section.hash(state);
+                }
                 in_use_index += 1;
+            }
+        }
+    }
+}
 impl PartialEq for MonomorphKey {
     fn eq(&self, other: &Self) -> bool {
         if self.in_use.is_empty() {
             return self.parts == other.parts;
         } else {
             // Outer type does not match
             if self.parts[0] != other.parts[0] {
                 return false;
+            }
             debug_assert_eq!(self.parts[0].num_embedded() as usize, self.in_use.len());
             let mut iter_self = ConcreteTypeIter::new(self.parts.as_slice(), 0);
             let mut iter_other = ConcreteTypeIter::new(other.parts.as_slice(), 0);
             let mut index = 0;
             while let Some(section_self) = iter_self.next() {
                 let section_other = iter_other.next().unwrap();
                 let in_use = self.in_use[index];
                 index += 1;
                 if !in_use {
                     continue;
+                }
                 if section_self != section_other {
                     return false;
+                }
+            }
             return true;
+        }
+    }
+}
 impl Eq for MonomorphKey {}
 use std::cell::UnsafeCell;
 /// Lookup table for monomorphs. Wrapped in a special struct because we don't
 /// want to allocate for each lookup (what we really want is a HashMap that
 /// exposes it CompareFn and HashFn, but whatevs).
 pub(crate) struct MonomorphTable {
     lookup: HashMap<MonomorphKey, i32>, // indexes into `monomorphs`
     pub(crate) monomorphs: Vec<TypeMonomorph>,
     // We use an UnsafeCell because this is only used internally per call to
     // `get_monomorph_index` calls. This is safe because `&TypeMonomorph`s
     // retrieved for this class remain valid when the key is mutated and the
     // type table is not multithreaded.
     //
     // I added this because we don't want to allocate for each lookup, hence we
     // need a reusable `key` internal to this class. This in turn makes
     // `get_monomorph_index` a mutable call. Now the code that calls this
     // function (even though we're not mutating the table!) needs a lot of extra
     // boilerplate. I opted for the `UnsafeCell` instead of the boilerplate.
     key: UnsafeCell<MonomorphKey>,
+}
 impl MonomorphTable {
     fn new() -> Self {
         return Self {
             lookup: HashMap::with_capacity(256),
             monomorphs: Vec::with_capacity(256),
             key: UnsafeCell::new(MonomorphKey{
                 parts: Vec::with_capacity(32),
                 in_use: Vec::with_capacity(32),
             })
+        }
+    }
     fn insert_with_zero_size_and_alignment(&mut self, concrete_type: ConcreteType, in_use: &[PolymorphicVariable], variant: MonomorphVariant) -> i32 {
         let key = MonomorphKey{
             parts: Vec::from(concrete_type.parts.as_slice()),
             in_use: in_use.iter().map(|v| v.is_in_use).collect(),
         };
         let index = self.monomorphs.len();
         let _result = self.lookup.insert(key, index as i32);
         debug_assert!(_result.is_none()); // did not exist yet
         self.monomorphs.push(TypeMonomorph{
             concrete_type,
             size: 0,
             alignment: 0,
             variant,
         });
         return index as i32;
+    }
     fn get_monomorph_index(&self, parts: &[ConcreteTypePart], in_use: &[PolymorphicVariable]) -> Option<i32> {
         // Note: the entire goal of this internal `MonomorphKey` is to prevent
         // allocation. So:
         let key = unsafe {
             let key = &mut *self.key.get();
             key.parts.clear();
             key.parts.extend_from_slice(parts);
             key.in_use.clear();
             key.in_use.extend(in_use.iter().map(|v| v.is_in_use));
             &*key
         };
         match self.lookup.get(key) {
             Some(index) => return Some(*index),
             None => return None,
+        }
+    }
     #[inline]
     fn get(&self, index: i32) -> &TypeMonomorph {
         debug_assert!(index >= 0);
         return &self.monomorphs[index as usize];
+    }
     #[inline]
     fn get_mut(&mut self, index: i32) -> &mut TypeMonomorph {
         debug_assert!(index >= 0);
         return &mut self.monomorphs[index as usize];
+    }
     fn get_monomorph_size_alignment(&self, index: i32) -> Option<(usize, usize)> {
         let monomorph = self.get(index);
         if monomorph.size == 0 && monomorph.alignment == 0 {
             // If both are zero, then we wish to mean: we haven't actually
             // computed the size and alignment yet. So:
             return None;
         } else {
             return Some((monomorph.size, monomorph.alignment));
+        }
+    }
+}
 //------------------------------------------------------------------------------
 // Type table
 //------------------------------------------------------------------------------
 // Programmer note: keep this struct free of dynamically allocated memory
 #[derive(Clone)]
 struct TypeLoopBreadcrumb {
     definition_id: DefinitionId,
     monomorph_idx: usize,
     next_member: usize,
     next_embedded: usize, // for unions, the index into the variant's embedded types
     definition_id: DefinitionId, // TODO: Check if it can be removed?
     monomorph_idx: i32,
     next_member: u32,
     next_embedded: u32, // for unions, the index into the variant's embedded types
+}
 #[derive(Clone)]
 struct MemoryBreadcrumb {
     definition_id: DefinitionId,
-    monomorph_idx: usize,
+    monomorph_idx: i32,
     next_member: usize,
     next_embedded: usize,
     first_size_alignment_idx: usize,
+}
 #[derive(Debug, PartialEq, Eq)]
 enum TypeLoopResult {
     TypeExists,
     PushBreadcrumb(DefinitionId, ConcreteType),
     TypeLoop(usize), // index into vec of breadcrumbs at which the type matched
+}
 enum MemoryLayoutResult {
     TypeExists(usize, usize), // (size, alignment)
     PushBreadcrumb(MemoryBreadcrumb),
+}
 // TODO: @Optimize, initial memory-unoptimized implementation
 struct TypeLoopEntry {
     definition_id: DefinitionId,
-    monomorph_idx: usize,
+    monomorph_idx: i32,
     is_union: bool,
+}
 struct TypeLoop {
     members: Vec<TypeLoopEntry>
+}
 pub struct TypeTable {
     /// Lookup from AST DefinitionId to a defined type. Considering possible
     /// polymorphs is done inside the `DefinedType` struct.
     lookup: HashMap<DefinitionId, DefinedType>,
     /// Lookup from AST DefinitionId to a defined type. Also lookups for
     /// concrete type to monomorphs
     pub(crate) type_lookup: HashMap<DefinitionId, DefinedType>,
     pub(crate) mono_lookup: MonomorphTable,
     /// Breadcrumbs left behind while trying to find type loops. Also used to
     /// determine sizes of types when all type loops are detected.
     type_loop_breadcrumbs: Vec<TypeLoopBreadcrumb>,
     type_loops: Vec<TypeLoop>,
     /// Stores all encountered types during type loop detection. Used afterwards
     /// to iterate over all types in order to compute size/alignment.
     encountered_types: Vec<TypeLoopEntry>,
     /// Breadcrumbs and temporary storage during memory layout computation.
     memory_layout_breadcrumbs: Vec<MemoryBreadcrumb>,
     size_alignment_stack: Vec<(usize, usize)>,
+}
 impl TypeTable {
     /// Construct a new type table without any resolved types.
     pub(crate) fn new() -> Self {
         Self{
             lookup: HashMap::new(),
             type_lookup: HashMap::with_capacity(128),
             mono_lookup: MonomorphTable::new(),
             type_loop_breadcrumbs: Vec::with_capacity(32),
             type_loops: Vec::with_capacity(8),
             encountered_types: Vec::with_capacity(32),
             memory_layout_breadcrumbs: Vec::with_capacity(32),
             size_alignment_stack: Vec::with_capacity(64),
+        }
+    }
     /// Iterates over all defined types (polymorphic and non-polymorphic) and
     /// add their types in two passes. In the first pass we will just add the
     /// base types (we will not consider monomorphs, and we will not compute
     /// byte sizes). In the second pass we will compute byte sizes of
     /// non-polymorphic types, and potentially the monomorphs that are embedded
     /// in those types.
     pub(crate) fn build_base_types(&mut self, modules: &mut [Module], ctx: &mut PassCtx) -> Result<(), ParseError> {
         // Make sure we're allowed to cast root_id to index into ctx.modules
         debug_assert!(modules.iter().all(|m| m.phase >= ModuleCompilationPhase::DefinitionsParsed));
-        debug_assert!(self.lookup.is_empty());
+        debug_assert!(self.type_lookup.is_empty());
         if cfg!(debug_assertions) {
             for (index, module) in modules.iter().enumerate() {
                 debug_assert_eq!(index, module.root_id.index as usize);
+            }
+        }
         // Use context to guess hashmap size of the base types
         let reserve_size = ctx.heap.definitions.len();
-        self.lookup.reserve(reserve_size);
+        self.type_lookup.reserve(reserve_size);
         // Resolve all base types
         for definition_idx in 0..ctx.heap.definitions.len() {
             let definition_id = ctx.heap.definitions.get_id(definition_idx);
             let definition = &ctx.heap[definition_id];
             match definition {
                 Definition::Enum(_) => self.build_base_enum_definition(modules, ctx, definition_id)?,
                 Definition::Union(_) => self.build_base_union_definition(modules, ctx, definition_id)?,
                 Definition::Struct(_) => self.build_base_struct_definition(modules, ctx, definition_id)?,
                 Definition::Function(_) => self.build_base_function_definition(modules, ctx, definition_id)?,
                 Definition::Component(_) => self.build_base_component_definition(modules, ctx, definition_id)?,
+            }
+        }
-        debug_assert_eq!(self.lookup.len(), reserve_size, "mismatch in reserved size of type table"); // NOTE: Temp fix for builtin functions
+        debug_assert_eq!(self.type_lookup.len(), reserve_size, "mismatch in reserved size of type table"); // NOTE: Temp fix for builtin functions
         for module in modules.iter_mut() {
             module.phase = ModuleCompilationPhase::TypesAddedToTable;
+        }
         // Go through all types again, lay out all types that are not
         // polymorphic. This might cause us to lay out types that are monomorphs
         // of polymorphic types.
         for definition_idx in 0..ctx.heap.definitions.len() {
             let definition_id = ctx.heap.definitions.get_id(definition_idx);
             let poly_type = self.lookup.get(&definition_id).unwrap();
             let poly_type = self.type_lookup.get(&definition_id).unwrap();
             if !poly_type.definition.type_class().is_data_type() || !poly_type.poly_vars.is_empty() {
                 continue;
+            }
             // Here we explicitly want to instantiate types which have no
             // polymorphic arguments (even if it has phantom polymorphic
             // arguments) because otherwise the user will see very weird
             // error messages.
             if poly_type.definition.type_class().is_data_type() && poly_type.poly_vars.is_empty() && poly_type.num_monomorphs() == 0 {
             // If here then the type is a data type without polymorphic
             // variables, but we might have instantiated it already, so:
             let concrete_parts = [ConcreteTypePart::Instance(definition_id, 0)];
             let mono_index = self.mono_lookup.get_monomorph_index(&concrete_parts, &[]);
             if mono_index.is_none() {
                 self.detect_and_resolve_type_loops_for(
                     modules, ctx.heap,
                     ConcreteType{
                         parts: vec![ConcreteTypePart::Instance(definition_id, 0)]
                     },
                 )?;
                 self.lay_out_memory_for_encountered_types(ctx.arch);
+            }
+        }
         Ok(())
+    }
     /// Retrieves base definition from type table. We must be able to retrieve
     /// it as we resolve all base types upon type table construction (for now).
     /// However, in the future we might do on-demand type resolving, so return
     /// an option anyway
     #[inline]
     pub(crate) fn get_base_definition(&self, definition_id: &DefinitionId) -> Option<&DefinedType> {
-        self.lookup.get(&definition_id)
+        self.type_lookup.get(&definition_id)
+    }
     /// Returns the index into the monomorph type array if the procedure type
     /// already has a (reserved) monomorph.
     pub(crate) fn get_procedure_monomorph_index(&self, definition_id: &DefinitionId, types: &ConcreteType) -> Option<i32> {
         let def = self.lookup.get(definition_id).unwrap();
         let monos = def.definition.procedure_monomorphs();
         return monos.iter()
             .position(|v| v.concrete_type == *types)
             .map(|v| v as i32);
     #[inline]
     pub(crate) fn get_procedure_monomorph_index(&self, definition_id: &DefinitionId, type_parts: &[ConcreteTypePart]) -> Option<i32> {
         let base_type = self.type_lookup.get(definition_id).unwrap();
         return self.mono_lookup.get_monomorph_index(type_parts, &base_type.poly_vars);
+    }
     #[inline]
     pub(crate) fn get_monomorph(&self, monomorph_index: i32) -> &TypeMonomorph {
         return self.mono_lookup.get(monomorph_index);
+    }
     /// Returns a mutable reference to a procedure's monomorph expression data.
     /// Used by typechecker to fill in previously reserved type information
     pub(crate) fn get_procedure_expression_data_mut(&mut self, definition_id: &DefinitionId, monomorph_idx: i32) -> &mut ProcedureMonomorph {
         debug_assert!(monomorph_idx >= 0);
         let def = self.lookup.get_mut(definition_id).unwrap();
         let monomorphs = def.definition.procedure_monomorphs_mut();
         return &mut monomorphs[monomorph_idx as usize];
     #[inline]
     pub(crate) fn get_procedure_monomorph_mut(&mut self, monomorph_index: i32) -> &mut ProcedureMonomorph {
         debug_assert!(monomorph_index >= 0);
         let monomorph = self.mono_lookup.get_mut(monomorph_index);
         return monomorph.variant.as_procedure_mut();
+    }
     pub(crate) fn get_procedure_expression_data(&self, definition_id: &DefinitionId, monomorph_idx: i32) -> &ProcedureMonomorph {
         debug_assert!(monomorph_idx >= 0);
         let def = self.lookup.get(definition_id).unwrap();
         let monomorphs = def.definition.procedure_monomorphs();
         return &monomorphs[monomorph_idx as usize];
     #[inline]
     pub(crate) fn get_procedure_monomorph(&self, monomorph_index: i32) -> &ProcedureMonomorph {
         debug_assert!(monomorph_index >= 0);
         let monomorph = self.mono_lookup.get(monomorph_index);
         return monomorph.variant.as_procedure();
+    }
     /// Reserves space for a monomorph of a polymorphic procedure. The index
     /// will point into a (reserved) slot of the array of expression types. The
     /// monomorph may NOT exist yet (because the reservation implies that we're
     /// going to be performing typechecking on it, and we don't want to
     /// check the same monomorph twice)
     pub(crate) fn reserve_procedure_monomorph_index(&mut self, definition_id: &DefinitionId, concrete_type: ConcreteType) -> i32 {
         let def = self.lookup.get_mut(definition_id).unwrap();
         let mono_types = def.definition.procedure_monomorphs_mut();
         debug_assert!(def.is_polymorph == (concrete_type.parts.len() != 1));
         debug_assert!(!mono_types.iter().any(|v| v.concrete_type == concrete_type));
         let mono_idx = mono_types.len();
         mono_types.push(ProcedureMonomorph{
             concrete_type,
         let base_type = self.type_lookup.get_mut(definition_id).unwrap();
         let mono_index = self.mono_lookup.insert_with_zero_size_and_alignment(
             concrete_type, &base_type.poly_vars, MonomorphVariant::Procedure(ProcedureMonomorph{
                 arg_types: Vec::new(),
                 expr_data: Vec::new(),
         });
             })
         );
-        return mono_idx as i32;
+        return mono_index;
+    }
     /// Adds a datatype polymorph to the type table. Will not add the
     /// monomorph if it is already present, or if the type's polymorphic
     /// variables are all unused.
     /// TODO: Fix signature
     pub(crate) fn add_data_monomorph(
         &mut self, modules: &[Module], heap: &Heap, arch: &TargetArch, definition_id: DefinitionId, concrete_type: ConcreteType
     ) -> Result<i32, ParseError> {
         debug_assert_eq!(definition_id, get_concrete_type_definition(&concrete_type));
         // Check if the monomorph already exists
         let poly_type = self.lookup.get_mut(&definition_id).unwrap();
         if let Some(idx) = poly_type.get_monomorph_index(&concrete_type.parts) {
             return Ok(idx as i32);
         let poly_type = self.type_lookup.get_mut(&definition_id).unwrap();
         if let Some(idx) = self.mono_lookup.get_monomorph_index(&concrete_type.parts, &poly_type.poly_vars) {
             return Ok(idx);
+        }
         // Doesn't exist, so instantiate a monomorph and determine its memory
         // layout.
         self.detect_and_resolve_type_loops_for(modules, heap, concrete_type)?;
         debug_assert_eq!(self.encountered_types[0].definition_id, definition_id);
         let mono_idx = self.encountered_types[0].monomorph_idx;
         self.lay_out_memory_for_encountered_types(arch);
         return Ok(mono_idx as i32);
+    }
     //--------------------------------------------------------------------------
     // Building base types
     //--------------------------------------------------------------------------
     /// Builds the base type for an enum. Will not compute byte sizes
     fn build_base_enum_definition(&mut self, modules: &[Module], ctx: &mut PassCtx, definition_id: DefinitionId) -> Result<(), ParseError> {
-        debug_assert!(!self.lookup.contains_key(&definition_id), "base enum already built");
+        debug_assert!(!self.type_lookup.contains_key(&definition_id), "base enum already built");
         let definition = ctx.heap[definition_id].as_enum();
         let root_id = definition.defined_in;
         // Determine enum variants
         let mut enum_value = -1;
         let mut variants = Vec::with_capacity(definition.variants.len());
         for variant in &definition.variants {
             if enum_value == i64::MAX {
                 let source = &modules[definition.defined_in.index as usize].source;
                 return Err(ParseError::new_error_str_at_span(
                     source, variant.identifier.span,
                     "this enum variant has an integer value that is too large"
                 ));
+            }
             enum_value += 1;
             if let EnumVariantValue::Integer(explicit_value) = variant.value {
                 enum_value = explicit_value;
+            }
             variants.push(EnumVariant{
                 identifier: variant.identifier.clone(),
                 value: enum_value,
             });
+        }
         // Determine tag size
         let mut min_enum_value = 0;
         let mut max_enum_value = 0;
         if !variants.is_empty() {
             min_enum_value = variants[0].value;
             max_enum_value = variants[0].value;
             for variant in variants.iter().skip(1) {
                 min_enum_value = min_enum_value.min(variant.value);
                 max_enum_value = max_enum_value.max(variant.value);
+            }
+        }
         let (tag_type, size_and_alignment) = Self::variant_tag_type_from_values(min_enum_value, max_enum_value);
         // Enum names and polymorphic args do not conflict
         Self::check_identifier_collision(
             modules, root_id, &variants, |variant| &variant.identifier, "enum variant"
         )?;
         // Polymorphic arguments cannot appear as embedded types, because
         // they can only consist of integer variants.
         Self::check_poly_args_collision(modules, ctx, root_id, &definition.poly_vars)?;
         let poly_vars = Self::create_polymorphic_variables(&definition.poly_vars);
-        self.lookup.insert(definition_id, DefinedType {
+        self.type_lookup.insert(definition_id, DefinedType {
             ast_root: root_id,
             ast_definition: definition_id,
             definition: DefinedTypeVariant::Enum(EnumType{
                 variants,
                 monomorphs: Vec::new(),
                 minimum_tag_value: min_enum_value,
                 maximum_tag_value: max_enum_value,
                 tag_type,
                 size: size_and_alignment,
                 alignment: size_and_alignment
             }),
             poly_vars,
             is_polymorph: false,
         });
         return Ok(());
+    }
     /// Builds the base type for a union. Will compute byte sizes.
     fn build_base_union_definition(&mut self, modules: &[Module], ctx: &mut PassCtx, definition_id: DefinitionId) -> Result<(), ParseError> {
-        debug_assert!(!self.lookup.contains_key(&definition_id), "base union already built");
+        debug_assert!(!self.type_lookup.contains_key(&definition_id), "base union already built");
         let definition = ctx.heap[definition_id].as_union();
         let root_id = definition.defined_in;
         // Check all variants and their embedded types
         let mut variants = Vec::with_capacity(definition.variants.len());
         let mut tag_counter = 0;
         for variant in &definition.variants {
             for embedded in &variant.value {
                 Self::check_member_parser_type(
                     modules, ctx, root_id, embedded, false
                 )?;
+            }
             variants.push(UnionVariant{
                 identifier: variant.identifier.clone(),
                 embedded: variant.value.clone(),
                 tag_value: tag_counter,
             });
             tag_counter += 1;
+        }
         let mut max_tag_value = 0;
         if tag_counter != 0 {
             max_tag_value = tag_counter - 1
+        }
         let (tag_type, tag_size) = Self::variant_tag_type_from_values(0, max_tag_value);
         // Make sure there are no conflicts in identifiers
         Self::check_identifier_collision(
             modules, root_id, &variants, |variant| &variant.identifier, "union variant"
         )?;
         Self::check_poly_args_collision(modules, ctx, root_id, &definition.poly_vars)?;
         // Construct internal representation of union
         let mut poly_vars = Self::create_polymorphic_variables(&definition.poly_vars);
         for variant in &definition.variants {
             for embedded in &variant.value {
                 Self::mark_used_polymorphic_variables(&mut poly_vars, embedded);
+            }
+        }
         let is_polymorph = poly_vars.iter().any(|arg| arg.is_in_use);
-        self.lookup.insert(definition_id, DefinedType{
+        self.type_lookup.insert(definition_id, DefinedType{
             ast_root: root_id,
             ast_definition: definition_id,
             definition: DefinedTypeVariant::Union(UnionType{
                 variants,
                 monomorphs: Vec::new(),
                 tag_type,
                 tag_size,
             }),
             definition: DefinedTypeVariant::Union(UnionType{ variants, tag_type, tag_size }),
             poly_vars,
             is_polymorph
         });
         return Ok(());
+    }
     /// Builds base struct type. Will not compute byte sizes.
     fn build_base_struct_definition(&mut self, modules: &[Module], ctx: &mut PassCtx, definition_id: DefinitionId) -> Result<(), ParseError> {
-        debug_assert!(!self.lookup.contains_key(&definition_id), "base struct already built");
+        debug_assert!(!self.type_lookup.contains_key(&definition_id), "base struct already built");
         let definition = ctx.heap[definition_id].as_struct();
         let root_id = definition.defined_in;
         // Check all struct fields and construct internal representation
         let mut fields = Vec::with_capacity(definition.fields.len());
         for field in &definition.fields {
             Self::check_member_parser_type(
                 modules, ctx, root_id, &field.parser_type, false
             )?;
             fields.push(StructField{
                 identifier: field.field.clone(),
                 parser_type: field.parser_type.clone(),
             });
+        }
         // Make sure there are no conflicting variables
         Self::check_identifier_collision(
             modules, root_id, &fields, |field| &field.identifier, "struct field"
         )?;
         Self::check_poly_args_collision(modules, ctx, root_id, &definition.poly_vars)?;
         // Construct base type in table
         let mut poly_vars = Self::create_polymorphic_variables(&definition.poly_vars);
         for field in &fields {
             Self::mark_used_polymorphic_variables(&mut poly_vars, &field.parser_type);
+        }
         let is_polymorph = poly_vars.iter().any(|arg| arg.is_in_use);
-        self.lookup.insert(definition_id, DefinedType{
+        self.type_lookup.insert(definition_id, DefinedType{
             ast_root: root_id,
             ast_definition: definition_id,
             definition: DefinedTypeVariant::Struct(StructType{
                 fields,
                 monomorphs: Vec::new(),
             }),
             definition: DefinedTypeVariant::Struct(StructType{ fields }),
             poly_vars,
             is_polymorph
         });
         return Ok(())
+    }
     /// Builds base function type.
     fn build_base_function_definition(&mut self, modules: &[Module], ctx: &mut PassCtx, definition_id: DefinitionId) -> Result<(), ParseError> {
-        debug_assert!(!self.lookup.contains_key(&definition_id), "base function already built");
+        debug_assert!(!self.type_lookup.contains_key(&definition_id), "base function already built");
         let definition = ctx.heap[definition_id].as_function();
         let root_id = definition.defined_in;
         // Check and construct return types and argument types.
         debug_assert_eq!(definition.return_types.len(), 1, "not one return type");
         for return_type in &definition.return_types {
             Self::check_member_parser_type(
                 modules, ctx, root_id, return_type, definition.builtin
             )?;
+        }
         let mut arguments = Vec::with_capacity(definition.parameters.len());
         for parameter_id in &definition.parameters {
             let parameter = &ctx.heap[*parameter_id];
             Self::check_member_parser_type(
                 modules, ctx, root_id, &parameter.parser_type, definition.builtin
             )?;
             arguments.push(FunctionArgument{
                 identifier: parameter.identifier.clone(),
                 parser_type: parameter.parser_type.clone(),
             });
+        }
         // Check conflict of identifiers
         Self::check_identifier_collision(
             modules, root_id, &arguments, |arg| &arg.identifier, "function argument"
         )?;
         Self::check_poly_args_collision(modules, ctx, root_id, &definition.poly_vars)?;
         // Construct internal representation of function type
         let mut poly_vars = Self::create_polymorphic_variables(&definition.poly_vars);
         for return_type in &definition.return_types {
             Self::mark_used_polymorphic_variables(&mut poly_vars, return_type);
+        }
         for argument in &arguments {
             Self::mark_used_polymorphic_variables(&mut poly_vars, &argument.parser_type);
+        }
         let is_polymorph = poly_vars.iter().any(|arg| arg.is_in_use);
-        self.lookup.insert(definition_id, DefinedType{
+        self.type_lookup.insert(definition_id, DefinedType{
             ast_root: root_id,
             ast_definition: definition_id,
             definition: DefinedTypeVariant::Function(FunctionType{
                 return_types: definition.return_types.clone(),
                 arguments,
                 monomorphs: Vec::new(),
             }),
             definition: DefinedTypeVariant::Function(FunctionType{ return_types: definition.return_types.clone(), arguments }),
             poly_vars,
             is_polymorph
         });
         return Ok(());
+    }
     /// Builds base component type.
     fn build_base_component_definition(&mut self, modules: &[Module], ctx: &mut PassCtx, definition_id: DefinitionId) -> Result<(), ParseError> {
-        debug_assert!(!self.lookup.contains_key(&definition_id), "base component already built");
+        debug_assert!(!self.type_lookup.contains_key(&definition_id), "base component already built");
         let definition = &ctx.heap[definition_id].as_component();
         let root_id = definition.defined_in;
         // Check the argument types
         let mut arguments = Vec::with_capacity(definition.parameters.len());
         for parameter_id in &definition.parameters {
             let parameter = &ctx.heap[*parameter_id];
             Self::check_member_parser_type(
                 modules, ctx, root_id, &parameter.parser_type, false
             )?;
             arguments.push(FunctionArgument{
                 identifier: parameter.identifier.clone(),
                 parser_type: parameter.parser_type.clone(),
             });
+        }
         // Check conflict of identifiers
         Self::check_identifier_collision(
             modules, root_id, &arguments, |arg| &arg.identifier, "connector argument"
         )?;
         Self::check_poly_args_collision(modules, ctx, root_id, &definition.poly_vars)?;
         // Construct internal representation of component
         let mut poly_vars = Self::create_polymorphic_variables(&definition.poly_vars);
         for argument in &arguments {
             Self::mark_used_polymorphic_variables(&mut poly_vars, &argument.parser_type);
+        }
         let is_polymorph = poly_vars.iter().any(|arg| arg.is_in_use);
-        self.lookup.insert(definition_id, DefinedType{
+        self.type_lookup.insert(definition_id, DefinedType{
             ast_root: root_id,
             ast_definition: definition_id,
             definition: DefinedTypeVariant::Component(ComponentType{
                 variant: definition.variant,
                 arguments,
                 monomorphs: Vec::new()
             }),
             definition: DefinedTypeVariant::Component(ComponentType{ variant: definition.variant, arguments }),
             poly_vars,
             is_polymorph
         });
         Ok(())
+    }
     /// Will check if the member type (field of a struct, embedded type in a
     /// union variant) is valid.
     fn check_member_parser_type(
         modules: &[Module], ctx: &PassCtx, base_definition_root_id: RootId,
         member_parser_type: &ParserType, allow_special_compiler_types: bool
     ) -> Result<(), ParseError> {
         use ParserTypeVariant as PTV;
         for element in &member_parser_type.elements {
             match element.variant {
                 // Special cases
                 PTV::Void | PTV::InputOrOutput | PTV::ArrayLike | PTV::IntegerLike => {
                     if !allow_special_compiler_types {
                         unreachable!("compiler-only ParserTypeVariant in member type");
+                    }
                 },
                 // Builtin types, always valid
                 PTV::Message | PTV::Bool |
                 PTV::UInt8 | PTV::UInt16 | PTV::UInt32 | PTV::UInt64 |
                 PTV::SInt8 | PTV::SInt16 | PTV::SInt32 | PTV::SInt64 |
                 PTV::Character | PTV::String |
                 PTV::Array | PTV::Input | PTV::Output | PTV::Tuple(_) |
                 // Likewise, polymorphic variables are always valid
                 PTV::PolymorphicArgument(_, _) => {},
                 // Types that are not constructable, or types that are not
                 // allowed (and checked earlier)
                 PTV::IntegerLiteral | PTV::Inferred => {
                     unreachable!("illegal ParserTypeVariant within type definition");
                 },
                 // Finally, user-defined types
                 PTV::Definition(definition_id, _) => {
                     let definition = &ctx.heap[definition_id];
                     if !(definition.is_struct() || definition.is_enum() || definition.is_union()) {
                         let source = &modules[base_definition_root_id.index as usize].source;
                         return Err(ParseError::new_error_str_at_span(
                             source, element.element_span, "expected a datatype (a struct, enum or union)"
                         ));
+                    }
                     // Otherwise, we're fine
+                }
+            }
+        }
         // If here, then all elements check out
         return Ok(());
+    }
     /// Go through a list of identifiers and ensure that all identifiers have
     /// unique names
     fn check_identifier_collision<T: Sized, F: Fn(&T) -> &Identifier>(
         modules: &[Module], root_id: RootId, items: &[T], getter: F, item_name: &'static str
     ) -> Result<(), ParseError> {
         for (item_idx, item) in items.iter().enumerate() {
             let item_ident = getter(item);
             for other_item in &items[0..item_idx] {
                 let other_item_ident = getter(other_item);
                 if item_ident == other_item_ident {
                     let module_source = &modules[root_id.index as usize].source;
                     return Err(ParseError::new_error_at_span(
                         module_source, item_ident.span, format!("This {} is defined more than once", item_name)
                     ).with_info_at_span(
                         module_source, other_item_ident.span, format!("The other {} is defined here", item_name)
                     ));
+                }
+            }
+        }
         Ok(())
+    }
     /// Go through a list of polymorphic arguments and make sure that the
     /// arguments all have unique names, and the arguments do not conflict with
     /// any symbols defined at the module scope.
     fn check_poly_args_collision(
         modules: &[Module], ctx: &PassCtx, root_id: RootId, poly_args: &[Identifier]
     ) -> Result<(), ParseError> {
         // Make sure polymorphic arguments are unique and none of the
         // identifiers conflict with any imported scopes
         for (arg_idx, poly_arg) in poly_args.iter().enumerate() {
             for other_poly_arg in &poly_args[..arg_idx] {
                 if poly_arg == other_poly_arg {
                     let module_source = &modules[root_id.index as usize].source;
                     return Err(ParseError::new_error_str_at_span(
                         module_source, poly_arg.span,
                         "This polymorphic argument is defined more than once"
                     ).with_info_str_at_span(
                         module_source, other_poly_arg.span,
                         "It conflicts with this polymorphic argument"
                     ));
+                }
+            }
             // Check if identifier conflicts with a symbol defined or imported
             // in the current module
             if let Some(symbol) = ctx.symbols.get_symbol_by_name(SymbolScope::Module(root_id), poly_arg.value.as_bytes()) {
                 // We have a conflict
                 let module_source = &modules[root_id.index as usize].source;
                 let introduction_span = symbol.variant.span_of_introduction(ctx.heap);
                 return Err(ParseError::new_error_str_at_span(
                     module_source, poly_arg.span,
                     "This polymorphic argument conflicts with another symbol"
                 ).with_info_str_at_span(
                     module_source, introduction_span,
                     "It conflicts due to this symbol"
                 ));
+            }
+        }
         // All arguments are fine
         Ok(())
+    }
     //--------------------------------------------------------------------------
     // Detecting type loops
     //--------------------------------------------------------------------------
     /// Internal function that will detect type loops and check if they're
     /// resolvable. If so then the appropriate union variants will be marked as
     /// "living on heap". If not then a `ParseError` will be returned
     fn detect_and_resolve_type_loops_for(&mut self, modules: &[Module], heap: &Heap, concrete_type: ConcreteType) -> Result<(), ParseError> {
         // Programmer notes: what happens here is the we call
         // `check_member_for_type_loops` for a particular type's member, and
         // then take action using the return value:
         // 1. It might already be resolved: in this case it implies we don't
         //  have type loops, or they have been resolved.
         // 2. A new type is encountered. If so then it is added to the type loop
         //  breadcrumbs.
         // 3. A type loop is detected (implying the type is already resolved, or
         //  already exists in the type loop breadcrumbs).
         //
         // Using the breadcrumbs we incrementally check every member type of a
         // particular considered type (e.g. a struct field, tuple member), and
         // do the same as above. Note that when a breadcrumb is added we reserve
         // space in the monomorph storage, initialized to zero-values (i.e.
         // wrong values). The breadcrumbs keep track of how far and along we are
         // with resolving the member types.
         //
         // At the end we may have some type loops. If they're unresolvable then
         // we throw an error). If there are no type loops or they are all
         // resolvable then we end up with a list of `encountered_types`. These
         // are then used by `lay_out_memory_for_encountered_types`.
         use DefinedTypeVariant as DTV;
         debug_assert!(self.type_loop_breadcrumbs.is_empty());
         debug_assert!(self.type_loops.is_empty());
         debug_assert!(self.encountered_types.is_empty());
         // Push the initial breadcrumb
         let initial_breadcrumb = self.check_member_for_type_loops(&concrete_type);
         if let TypeLoopResult::PushBreadcrumb(definition_id, concrete_type) = initial_breadcrumb {
             self.handle_new_breadcrumb_for_type_loops(definition_id, concrete_type);
         } else {
             unreachable!();
+        }
         // Enter into the main resolving loop
         while !self.type_loop_breadcrumbs.is_empty() {
             // Because we might be modifying the breadcrumb array we need to
             let breadcrumb_idx = self.type_loop_breadcrumbs.len() - 1;
             let mut breadcrumb = self.type_loop_breadcrumbs[breadcrumb_idx].clone();
             let poly_type = self.lookup.get(&breadcrumb.definition_id).unwrap();
             // TODO: Also don't need DefinitionId here. So then only need mono_index, so then just
             //  do a switch on the monomorph, not on the base type.
             let resolve_result = if breadcrumb.definition_id.is_invalid() {
                 // We're dealing with a tuple
                 let monomorph = self.mono_lookup.get(breadcrumb.monomorph_idx).variant.as_tuple();
                 let num_members = monomorph.members.len() as u32;
                 let mut tuple_result = TypeLoopResult::TypeExists;
                 while breadcrumb.next_member < num_members {
                     let tuple_member = &monomorph.members[breadcrumb.next_member as usize];
                     tuple_result = self.check_member_for_type_loops(&tuple_member.concrete_type);
                     if tuple_result != TypeLoopResult::TypeExists {
                         break;
+                    }
             let resolve_result = match &poly_type.definition {
                     breadcrumb.next_member += 1;
+                }
                 tuple_result
             } else {
                 let poly_type = self.type_lookup.get(&breadcrumb.definition_id).unwrap();
                 match &poly_type.definition {
                     DTV::Enum(_) => {
                         TypeLoopResult::TypeExists
                     },
                     DTV::Union(definition) => {
                     let monomorph = &definition.monomorphs[breadcrumb.monomorph_idx];
                     let num_variants = monomorph.variants.len();
                         let monomorph = self.mono_lookup.get(breadcrumb.monomorph_idx).variant.as_union();
                         let num_variants = monomorph.variants.len() as u32;
                         let mut union_result = TypeLoopResult::TypeExists;
                         'member_loop: while breadcrumb.next_member < num_variants {
                         let mono_variant = &monomorph.variants[breadcrumb.next_member];
                         let num_embedded = mono_variant.embedded.len();
                             let mono_variant = &monomorph.variants[breadcrumb.next_member as usize];
                             let num_embedded = mono_variant.embedded.len() as u32;
                             while breadcrumb.next_embedded < num_embedded {
                             let mono_embedded = &mono_variant.embedded[breadcrumb.next_embedded];
+                                let mono_embedded = &mono_variant.embedded[breadcrumb.next_embedded as usize];
                                 union_result = self.check_member_for_type_loops(&mono_embedded.concrete_type);
                                 if union_result != TypeLoopResult::TypeExists {
                                     // In type loop or new breadcrumb pushed, so
                                     // break out of the resolving loop
                                     break 'member_loop;
+                                }
                                 breadcrumb.next_embedded += 1;
+                            }
                             breadcrumb.next_embedded = 0;
                             breadcrumb.next_member += 1
+                        }
                         union_result
                     },
                     DTV::Struct(definition) => {
                     let monomorph = &definition.monomorphs[breadcrumb.monomorph_idx];
                     let num_fields = monomorph.fields.len();
                         let monomorph = self.mono_lookup.get(breadcrumb.monomorph_idx).variant.as_struct();
                         let num_fields = monomorph.fields.len() as u32;
                         let mut struct_result = TypeLoopResult::TypeExists;
                         while breadcrumb.next_member < num_fields {
                         let mono_field = &monomorph.fields[breadcrumb.next_member];
+                            let mono_field = &monomorph.fields[breadcrumb.next_member as usize];
                             struct_result = self.check_member_for_type_loops(&mono_field.concrete_type);
                             if struct_result != TypeLoopResult::TypeExists {
                                 // Type loop or breadcrumb pushed, so break out of
                                 // the resolving loop
                                 break;
+                            }
                             breadcrumb.next_member += 1;
+                        }
                         struct_result
                     },
                     DTV::Function(_) | DTV::Component(_) => unreachable!(),
+                }
             };
             // Handle the result of attempting to resolve the current breadcrumb
             match resolve_result {
                 TypeLoopResult::TypeExists => {
                     // We finished parsing the type
                     self.type_loop_breadcrumbs.pop();
                 },
                 TypeLoopResult::PushBreadcrumb(definition_id, concrete_type) => {
                     // We recurse into the member type.
                     self.type_loop_breadcrumbs[breadcrumb_idx] = breadcrumb;
                     self.handle_new_breadcrumb_for_type_loops(definition_id, concrete_type);
                 },
                 TypeLoopResult::TypeLoop(first_idx) => {
                     // Because we will be modifying breadcrumbs within the
                     // type-loop handling code, put back the modified breadcrumb
                     self.type_loop_breadcrumbs[breadcrumb_idx] = breadcrumb;
                     // We're in a type loop. Add the type loop
                     let mut loop_members = Vec::with_capacity(self.type_loop_breadcrumbs.len() - first_idx);
                     let mut contains_union = false;
                     for breadcrumb_idx in first_idx..self.type_loop_breadcrumbs.len() {
                         let breadcrumb = &mut self.type_loop_breadcrumbs[breadcrumb_idx];
                         let mut is_union = false;
                         let entry = self.lookup.get_mut(&breadcrumb.definition_id).unwrap();
                         let entry = self.type_lookup.get_mut(&breadcrumb.definition_id).unwrap();
                         // TODO: Match on monomorph directly here
                         match &mut entry.definition {
                             DTV::Union(definition) => {
                                 // Mark the currently processed variant as requiring heap
                                 // allocation, then advance the *embedded* type. The loop above
                                 // will then take care of advancing it to the next *member*.
                                 let monomorph = &mut definition.monomorphs[breadcrumb.monomorph_idx];
                                 let variant = &mut monomorph.variants[breadcrumb.next_member];
                                 let monomorph = self.mono_lookup.get_mut(breadcrumb.monomorph_idx).variant.as_union_mut();
                                 let variant = &mut monomorph.variants[breadcrumb.next_member as usize];
                                 variant.lives_on_heap = true;
                                 breadcrumb.next_embedded += 1;
                                 is_union = true;
                                 contains_union = true;
                             },
                             _ => {}, // else: we don't care for now
+                        }
                         loop_members.push(TypeLoopEntry{
                             definition_id: breadcrumb.definition_id,
                             monomorph_idx: breadcrumb.monomorph_idx,
                             is_union
                         });
+                    }
                     let new_type_loop = TypeLoop{ members: loop_members };
                     if !contains_union {
                         // No way to (potentially) break the union. So return a
                         // type loop error. This is because otherwise our
                         // breadcrumb resolver ends up in an infinite loop.
                         return Err(construct_type_loop_error(
                             self, &new_type_loop, modules, heap
                         ));
+                    }
                     self.type_loops.push(new_type_loop);
+                }
+            }
+        }
         // All breadcrumbs have been cleared. So now `type_loops` contains all
         // of the encountered type loops, and `encountered_types` contains a
         // list of all unique monomorphs we encountered.
         // The next step is to figure out if all of the type loops can be
         // broken. A type loop can be broken if at least one union exists in the
         // loop and that union ended up having variants that are not part of
         // a type loop.
         fn type_loop_source_span_and_message<'a>(
             modules: &'a [Module], heap: &Heap, defined_type: &DefinedType, monomorph_idx: usize, index_in_loop: usize
             modules: &'a [Module], heap: &Heap, mono_lookup: &MonomorphTable,
             defined_type: &DefinedType, monomorph_idx: i32, index_in_loop: usize
         ) -> (&'a InputSource, InputSpan, String) {
             // Note: because we will discover the type loop the *first* time we
             // instantiate a monomorph with the provided polymorphic arguments
             // (not all arguments are actually used in the type). We don't have
             // to care about a second instantiation where certain unused
             // polymorphic arguments are different.
             // TODO: Also remove match on defined_type, replace with mono lookup
             let monomorph_type = match &defined_type.definition {
                 DTV::Union(definition) => &definition.monomorphs[monomorph_idx].concrete_type,
                 DTV::Struct(definition) => &definition.monomorphs[monomorph_idx].concrete_type,
                 DTV::Union(definition) => &mono_lookup.get(monomorph_idx).concrete_type,
                 DTV::Struct(definition) => &mono_lookup.get(monomorph_idx).concrete_type,
                 DTV::Enum(_) | DTV::Function(_) | DTV::Component(_) =>
                     unreachable!(), // impossible to have an enum/procedure in a type loop
             };
             let type_name = monomorph_type.display_name(&heap);
             let message = if index_in_loop == 0 {
                 format!(
                     "encountered an infinitely large type for '{}' (which can be fixed by \
                     introducing a union type that has a variant whose embedded types are \
                     not part of a type loop, or do not have embedded types)",
                     type_name
+                )
             } else if index_in_loop == 1 {
                 format!("because it depends on the type '{}'", type_name)
             } else {
                 format!("which depends on the type '{}'", type_name)
             };
             let ast_definition = &heap[defined_type.ast_definition];
             let ast_root_id = ast_definition.defined_in();
             return (
                 &modules[ast_root_id.index as usize].source,
                 ast_definition.identifier().span,
                 message
             );
+        }
         fn construct_type_loop_error(table: &TypeTable, type_loop: &TypeLoop, modules: &[Module], heap: &Heap) -> ParseError {
             let first_entry = &type_loop.members[0];
-            let first_type = table.lookup.get(&first_entry.definition_id).unwrap();
+            let first_type = table.type_lookup.get(&first_entry.definition_id).unwrap();
             let (first_module, first_span, first_message) = type_loop_source_span_and_message(
                 modules, heap, first_type, first_entry.monomorph_idx, 0
+                modules, heap, &table.mono_lookup, first_type, first_entry.monomorph_idx, 0
             );
             let mut parse_error = ParseError::new_error_at_span(first_module, first_span, first_message);
             let mut error_counter = 1;
             for member_idx in 1..type_loop.members.len() {
                 let entry = &type_loop.members[member_idx];
                 let entry_type = table.lookup.get(&first_entry.definition_id).unwrap();
                 if entry.definition_id.is_invalid() {
                     // Don't display the tuples
                     continue;
+                }
                 let entry_type = table.type_lookup.get(&first_entry.definition_id).unwrap();
                 let (module, span, message) = type_loop_source_span_and_message(
-                    modules, heap, entry_type, entry.monomorph_idx, member_idx
+                    modules, heap, &table.mono_lookup, entry_type, entry.monomorph_idx, error_counter
                 );
                 parse_error = parse_error.with_info_at_span(module, span, message);
                 error_counter += 1;
+            }
             parse_error
+        }
         for type_loop in &self.type_loops {
             let mut can_be_broken = false;
             debug_assert!(!type_loop.members.is_empty());
             for entry in &type_loop.members {
                 if entry.is_union {
                     let base_type = self.lookup.get(&entry.definition_id).unwrap();
                     let monomorph = &base_type.definition.as_union().monomorphs[entry.monomorph_idx];
                     let monomorph = &self.mono_lookup.get(entry.monomorph_idx).variant.as_union();
                     debug_assert!(!monomorph.variants.is_empty()); // otherwise it couldn't be part of the type loop
                     let has_stack_variant = monomorph.variants.iter().any(|variant| !variant.lives_on_heap);
                     if has_stack_variant {
                         can_be_broken = true;
                         break;
+                    }
+                }
+            }
             if !can_be_broken {
                 // Construct a type loop error
                 return Err(construct_type_loop_error(self, type_loop, modules, heap));
+            }
+        }
         // If here, then all type loops have been resolved and we can lay out
         // all of the members
         self.type_loops.clear();
         return Ok(());
+    }
     /// Checks if the specified type needs to be resolved (i.e. we need to push
     /// a breadcrumb), is already resolved (i.e. we can continue with the next
     /// member of the currently considered type) or is in the process of being
     /// resolved (i.e. we're in a type loop). Because of borrowing rules we
     /// don't do any modifications of internal types here. Hence: if we
     /// return `PushBreadcrumb` then call `handle_new_breadcrumb_for_type_loops`
     /// to take care of storing the appropriate types.
     fn check_member_for_type_loops(&self, definition_type: &ConcreteType) -> TypeLoopResult {
         use ConcreteTypePart as CTP;
         // We're only interested in user-defined types, so exit if it is a
         // builtin of some sort.
         // Depending on the type, lookup if the type has already been visited
         // (i.e. either already has its memory layed out, or is part of a type
         // loop because we've already visited the type)
         debug_assert!(!definition_type.parts.is_empty());
         let definition_id = match &definition_type.parts[0] {
         let (definition_id, monomorph_index) = match &definition_type.parts[0] {
             CTP::Tuple(_) => {
                 let monomorph_index = self.mono_lookup.get_monomorph_index(&definition_type.parts, &[]);
                 (DefinitionId::new_invalid(), monomorph_index)
             },
             CTP::Instance(definition_id, _) |
             CTP::Function(definition_id, _) |
             CTP::Component(definition_id, _) => {
                 *definition_id
                 let base_type = self.type_lookup.get(definition_id).unwrap();
                 let monomorph_index = self.mono_lookup.get_monomorph_index(&definition_type.parts, &base_type.poly_vars);
                 (*definition_id, monomorph_index)
             },
             _ => {
                 return TypeLoopResult::TypeExists
             },
         };
         let base_type = self.lookup.get(&definition_id).unwrap();
         if let Some(mono_idx) = base_type.get_monomorph_index(&definition_type.parts) {
             // Monomorph is already known. Check if it is present in the
             // breadcrumbs. If so, then we are in a type loop
         if let Some(monomorph_index) = monomorph_index {
             for (breadcrumb_idx, breadcrumb) in self.type_loop_breadcrumbs.iter().enumerate() {
-                if breadcrumb.definition_id == definition_id && breadcrumb.monomorph_idx == mono_idx {
+                if breadcrumb.monomorph_idx == monomorph_index {
                     return TypeLoopResult::TypeLoop(breadcrumb_idx);
+                }
+            }
             return TypeLoopResult::TypeExists;
+        }
         // Type is not yet known, so we need to insert it into the lookup and
         // push a new breadcrumb.
         return TypeLoopResult::PushBreadcrumb(definition_id, definition_type.clone());
+    }
     /// Handles the `PushBreadcrumb` result for a `check_member_for_type_loops`
     /// call.
     fn handle_new_breadcrumb_for_type_loops(&mut self, definition_id: DefinitionId, definition_type: ConcreteType) {
         use DefinedTypeVariant as DTV;
         use ConcreteTypePart as CTP;
         let base_type = self.lookup.get_mut(&definition_id).unwrap();
         let mut is_union = false;
         let monomorph_idx = match &mut base_type.definition {
             DTV::Enum(definition) => {
                 debug_assert!(definition.monomorphs.is_empty());
                 definition.monomorphs.push(EnumMonomorph{
                     concrete_type: definition_type,
         let monomorph_index = match &definition_type.parts[0] {
             CTP::Tuple(num_embedded) => {
                 debug_assert!(definition_id.is_invalid()); // because tuples do not have an associated `DefinitionId`
                 let mut members = Vec::with_capacity(*num_embedded as usize);
                 for section in ConcreteTypeIter::new(&definition_type.parts, 0) {
                     members.push(TupleMonomorphMember{
                         concrete_type: ConcreteType{ parts: Vec::from(section) },
                         size: 0,
                         alignment: 0,
                         offset: 0
                     });
+                }
                 let monomorph_index = self.mono_lookup.insert_with_zero_size_and_alignment(
                     definition_type, &[],
                     MonomorphVariant::Tuple(TupleMonomorph{
                         members,
                     })
                 );
                 monomorph_index
             },
             CTP::Instance(_check_definition_id, _) => {
                 debug_assert_eq!(definition_id, *_check_definition_id); // because this is how `definition_id` was determined
                 let base_type = self.type_lookup.get_mut(&definition_id).unwrap();
                 let monomorph_index = match &mut base_type.definition {
                     DTV::Enum(definition) => {
                         // TODO: Is this correct?
                         let mono_index = self.mono_lookup.insert_with_zero_size_and_alignment(
                             definition_type, &base_type.poly_vars, MonomorphVariant::Enum
                         );
                         mono_index
                     },
                     DTV::Union(definition) => {
                         // Create all the variants with their concrete types
                         let mut mono_variants = Vec::with_capacity(definition.variants.len());
                         for poly_variant in &definition.variants {
                             let mut mono_embedded = Vec::with_capacity(poly_variant.embedded.len());
                             for poly_embedded in &poly_variant.embedded {
                                 let mono_concrete = Self::construct_concrete_type(poly_embedded, &definition_type);
                                 mono_embedded.push(UnionMonomorphEmbedded{
                                     concrete_type: mono_concrete,
                                     size: 0,
                                     alignment: 0,
                                     offset: 0
                                 });
+                            }
                             mono_variants.push(UnionMonomorphVariant{
                                 lives_on_heap: false,
                                 embedded: mono_embedded,
                             })
+                        }
                 let mono_idx = definition.monomorphs.len();
                 definition.monomorphs.push(UnionMonomorph{
                     concrete_type: definition_type,
                         let mono_index = self.mono_lookup.insert_with_zero_size_and_alignment(
                             definition_type, &base_type.poly_vars,
                             MonomorphVariant::Union(UnionMonomorph{
                                 variants: mono_variants,
                     stack_size: 0,
                     stack_alignment: 0,
                                 heap_size: 0,
                                 heap_alignment: 0
                 });
                             })
                         );
                         is_union = true;
-                mono_idx
+                        mono_index
                     },
                     DTV::Struct(definition) => {
                         let mut mono_fields = Vec::with_capacity(definition.fields.len());
                         for poly_field in &definition.fields {
                             let mono_concrete = Self::construct_concrete_type(&poly_field.parser_type, &definition_type);
                             mono_fields.push(StructMonomorphField{
                                 concrete_type: mono_concrete,
                                 size: 0,
                                 alignment: 0,
                                 offset: 0
                             })
+                        }
                 let mono_idx = definition.monomorphs.len();
                 definition.monomorphs.push(StructMonomorph{
                     concrete_type: definition_type,
                     fields: mono_fields,
                     size: 0,
                     alignment: 0
                 });
                         let mono_index = self.mono_lookup.insert_with_zero_size_and_alignment(
                             definition_type, &base_type.poly_vars,
                             MonomorphVariant::Struct(StructMonomorph{ fields: mono_fields })
                         );
-                mono_idx
+                        mono_index
                     },
                     DTV::Function(_) | DTV::Component(_) => {
                         unreachable!("pushing type resolving breadcrumb for procedure type")
                     },
                 };
                 monomorph_index
             },
             _ => unreachable!(),
         };
         self.encountered_types.push(TypeLoopEntry{
             definition_id,
             monomorph_idx,
+            monomorph_idx: monomorph_index,
             is_union,
         });
         self.type_loop_breadcrumbs.push(TypeLoopBreadcrumb{
             definition_id,
             monomorph_idx,
+            monomorph_idx: monomorph_index,
             next_member: 0,
             next_embedded: 0,
         });
+    }
     /// Constructs a concrete type out of a parser type for a struct field or
     /// union embedded type. It will do this by looking up the polymorphic
     /// variables in the supplied concrete type. The assumption is that the
     /// polymorphic variable's indices correspond to the subtrees in the
     /// concrete type.
     fn construct_concrete_type(member_type: &ParserType, container_type: &ConcreteType) -> ConcreteType {
         use ParserTypeVariant as PTV;
         use ConcreteTypePart as CTP;
         // TODO: Combine with code in pass_typing.rs
         fn parser_to_concrete_part(part: &ParserTypeVariant) -> Option<ConcreteTypePart> {
             match part {
                 PTV::Void      => Some(CTP::Void),
                 PTV::Message   => Some(CTP::Message),
                 PTV::Bool      => Some(CTP::Bool),
                 PTV::UInt8     => Some(CTP::UInt8),
                 PTV::UInt16    => Some(CTP::UInt16),
                 PTV::UInt32    => Some(CTP::UInt32),
                 PTV::UInt64    => Some(CTP::UInt64),
                 PTV::SInt8     => Some(CTP::SInt8),
                 PTV::SInt16    => Some(CTP::SInt16),
                 PTV::SInt32    => Some(CTP::SInt32),
                 PTV::SInt64    => Some(CTP::SInt64),
                 PTV::Character => Some(CTP::Character),
                 PTV::String    => Some(CTP::String),
                 PTV::Array     => Some(CTP::Array),
                 PTV::Input     => Some(CTP::Input),
                 PTV::Output    => Some(CTP::Output),
                 PTV::Tuple(num) => Some(CTP::Tuple(*num)),
                 PTV::Definition(definition_id, num) => Some(CTP::Instance(*definition_id, *num)),
                 _              => None
+            }
+        }
         let mut parts = Vec::with_capacity(member_type.elements.len()); // usually a correct estimation, might not be
         for member_part in &member_type.elements {
             // Check if we have a regular builtin type
             if let Some(part) = parser_to_concrete_part(&member_part.variant) {
                 parts.push(part);
                 continue;
+            }
             // Not builtin, but if all code is working correctly, we only care
             // about the polymorphic argument at this point.
             if let PTV::PolymorphicArgument(_container_definition_id, poly_arg_idx) = member_part.variant {
                 debug_assert_eq!(_container_definition_id, get_concrete_type_definition(container_type));
                 let mut container_iter = container_type.embedded_iter(0);
                 for _ in 0..poly_arg_idx {
                     container_iter.next();
+                }
                 let poly_section = container_iter.next().unwrap();
                 parts.extend(poly_section);
                 continue;
+            }
             unreachable!("unexpected type part {:?} from {:?}", member_part, member_type);
+        }
         return ConcreteType{ parts };
+    }
     //--------------------------------------------------------------------------
     // Determining memory layout for types
     //--------------------------------------------------------------------------
     /// Should be called after type loops are detected (and resolved
     /// successfully). As a result of this call we expect the
     /// `encountered_types` array to be filled. We'll calculate size/alignment/
     /// offset values for those types in this routine.
     fn lay_out_memory_for_encountered_types(&mut self, arch: &TargetArch) {
         // Programmers note: this works like a little stack machine. We have
         // memory layout breadcrumbs which, like the type loop breadcrumbs, keep
         // track of the currently considered member type. This breadcrumb also
         // stores an index into the `size_alignment_stack`, which will be used
         // to store intermediate size/alignment pairs until all members are
         // resolved. Note that this `size_alignment_stack` is NOT an
         // optimization, we're working around borrowing rules here.
         use DefinedTypeVariant as DTV;
         // Just finished type loop detection, so we're left with the encountered
         // types only
         debug_assert!(self.type_loops.is_empty());
         debug_assert!(!self.encountered_types.is_empty());
         debug_assert!(self.memory_layout_breadcrumbs.is_empty());
         debug_assert!(self.size_alignment_stack.is_empty());
         // Push the first entry (the type we originally started with when we
         // were detecting type loops)
         let first_entry = &self.encountered_types[0];
         self.memory_layout_breadcrumbs.push(MemoryBreadcrumb{
             definition_id: first_entry.definition_id,
             monomorph_idx: first_entry.monomorph_idx,
             next_member: 0,
             next_embedded: 0,
             first_size_alignment_idx: 0,
         });
         // Enter the main resolving loop
         'breadcrumb_loop: while !self.memory_layout_breadcrumbs.is_empty() {
             let cur_breadcrumb_idx = self.memory_layout_breadcrumbs.len() - 1;
             let mut breadcrumb = self.memory_layout_breadcrumbs[cur_breadcrumb_idx].clone();
             let poly_type = self.lookup.get(&breadcrumb.definition_id).unwrap();
             // TODO: Same as above, replace lookup of base definition, should not
             //  be needed.
             if breadcrumb.definition_id.is_invalid() {
                 // Handle tuple
                 let mono_tuple = self.mono_lookup.get(breadcrumb.monomorph_idx).variant.as_tuple();
                 let num_members = mono_tuple.members.len();
                 while breadcrumb.next_member < num_members {
                     let mono_member = &mono_tuple.members[breadcrumb.next_member];
                     match self.get_memory_layout_or_breadcrumb(arch, &mono_member.concrete_type.parts) {
                         MemoryLayoutResult::TypeExists(size, alignment) => {
                             self.size_alignment_stack.push((size, alignment));
                         },
                         MemoryLayoutResult::PushBreadcrumb(new_breadcrumb) => {
                             self.memory_layout_breadcrumbs[cur_breadcrumb_idx] = breadcrumb;
                             self.memory_layout_breadcrumbs.push(new_breadcrumb);
                             continue 'breadcrumb_loop;
                         },
+                    }
                     breadcrumb.next_member += 1;
+                }
                 // If here then we can compute the memory layout of the tuple.
                 let mut cur_offset = 0;
                 let mut max_alignment = 0;
                 let mono_info = self.mono_lookup.get_mut(breadcrumb.monomorph_idx);
                 let mono_tuple = mono_info.variant.as_tuple_mut();
                 let mut size_alignment_index = breadcrumb.first_size_alignment_idx;
                 for member_index in 0..num_members {
                     let (member_size, member_alignment) = self.size_alignment_stack[size_alignment_index];
                     align_offset_to(&mut cur_offset, member_alignment);
                     size_alignment_index += 1;
                     let member = &mut mono_tuple.members[member_index];
                     member.size = member_size;
                     member.alignment = member_alignment;
                     member.offset = cur_offset;
                     cur_offset += member_size;
                     max_alignment = max_alignment.max(member_alignment);
+                }
                 mono_info.size = cur_offset;
                 mono_info.alignment = max_alignment;
                 self.size_alignment_stack.truncate(breadcrumb.first_size_alignment_idx);
             } else {
                 let poly_type = self.type_lookup.get(&breadcrumb.definition_id).unwrap();
                 match &poly_type.definition {
                     DTV::Enum(definition) => {
                         // Size should already be computed
                         debug_assert!(definition.size != 0 && definition.alignment != 0);
                         let mono_type = self.mono_lookup.get_mut(breadcrumb.monomorph_idx);
                         mono_type.size = definition.size;
                         mono_type.alignment = definition.alignment;
                     },
                     DTV::Union(definition) => {
                         // Retrieve size/alignment of each embedded type. We do not
                         // compute the offsets or total type sizes yet.
-                    let mono_type = &definition.monomorphs[breadcrumb.monomorph_idx];
+                        let mono_type = self.mono_lookup.get(breadcrumb.monomorph_idx).variant.as_union();
                         let num_variants = mono_type.variants.len();
                         while breadcrumb.next_member < num_variants {
                             let mono_variant = &mono_type.variants[breadcrumb.next_member];
                             if mono_variant.lives_on_heap {
                                 // To prevent type loops we made this a heap-
                                 // allocated variant. This implies we cannot
                                 // compute sizes of members at this point.
                             } else {
                                 let num_embedded = mono_variant.embedded.len();
                                 while breadcrumb.next_embedded < num_embedded {
                                     let mono_embedded = &mono_variant.embedded[breadcrumb.next_embedded];
                                     match self.get_memory_layout_or_breadcrumb(arch, &mono_embedded.concrete_type.parts) {
                                         MemoryLayoutResult::TypeExists(size, alignment) => {
                                             self.size_alignment_stack.push((size, alignment));
                                         },
                                         MemoryLayoutResult::PushBreadcrumb(new_breadcrumb) => {
                                             self.memory_layout_breadcrumbs[cur_breadcrumb_idx] = breadcrumb;
                                             self.memory_layout_breadcrumbs.push(new_breadcrumb);
                                             continue 'breadcrumb_loop;
+                                        }
+                                    }
                                     breadcrumb.next_embedded += 1;
+                                }
+                            }
                             breadcrumb.next_member += 1;
                             breadcrumb.next_embedded = 0;
+                        }
                         // If here then we can at least compute the stack size of
                         // the type, we'll have to come back at the very end to
                         // fill in the heap size/alignment/offset of each heap-
                         // allocated variant.
                         let mut max_size = definition.tag_size;
                         let mut max_alignment = definition.tag_size;
-                    let poly_type = self.lookup.get_mut(&breadcrumb.definition_id).unwrap();
+                        let poly_type = self.type_lookup.get_mut(&breadcrumb.definition_id).unwrap();
                         let definition = poly_type.definition.as_union_mut();
                     let mono_type = &mut definition.monomorphs[breadcrumb.monomorph_idx];
                         let mono_info = self.mono_lookup.get_mut(breadcrumb.monomorph_idx);
                         let mono_type = mono_info.variant.as_union_mut();
                         let mut size_alignment_idx = breadcrumb.first_size_alignment_idx;
                         for variant in &mut mono_type.variants {
                             // We're doing stack computations, so always start with
                             // the tag size/alignment.
                             let mut variant_offset = definition.tag_size;
                             let mut variant_alignment = definition.tag_size;
                             if variant.lives_on_heap {
                                 // Variant lives on heap, so just a pointer
                                 let (ptr_size, ptr_align) = arch.pointer_size_alignment;
                                 align_offset_to(&mut variant_offset, ptr_align);
                                 variant_offset += ptr_size;
                                 variant_alignment = variant_alignment.max(ptr_align);
                             } else {
                                 // Variant lives on stack, so walk all embedded
                                 // types.
                                 for embedded in &mut variant.embedded {
                                     let (size, alignment) = self.size_alignment_stack[size_alignment_idx];
                                     embedded.size = size;
                                     embedded.alignment = alignment;
                                     size_alignment_idx += 1;
                                     align_offset_to(&mut variant_offset, alignment);
                                     embedded.offset = variant_offset;
                                     variant_offset += size;
                                     variant_alignment = variant_alignment.max(alignment);
+                                }
                             };
                             max_size = max_size.max(variant_offset);
                             max_alignment = max_alignment.max(variant_alignment);
+                        }
                     mono_type.stack_size = max_size;
                     mono_type.stack_alignment = max_alignment;
                         mono_info.size = max_size;
                         mono_info.alignment = max_alignment;
                         self.size_alignment_stack.truncate(breadcrumb.first_size_alignment_idx);
                     },
                     DTV::Struct(definition) => {
                         // Retrieve size and alignment of each struct member. We'll
                         // compute the offsets once all of those are known
-                    let mono_type = &definition.monomorphs[breadcrumb.monomorph_idx];
+                        let mono_type = self.mono_lookup.get(breadcrumb.monomorph_idx).variant.as_struct();
                         let num_fields = mono_type.fields.len();
                         while breadcrumb.next_member < num_fields {
                             let mono_field = &mono_type.fields[breadcrumb.next_member];
                             match self.get_memory_layout_or_breadcrumb(arch, &mono_field.concrete_type.parts) {
                                 MemoryLayoutResult::TypeExists(size, alignment) => {
                                     self.size_alignment_stack.push((size, alignment))
                                 },
                                 MemoryLayoutResult::PushBreadcrumb(new_breadcrumb) => {
                                     self.memory_layout_breadcrumbs[cur_breadcrumb_idx] = breadcrumb;
                                     self.memory_layout_breadcrumbs.push(new_breadcrumb);
                                     continue 'breadcrumb_loop;
                                 },
+                            }
                             breadcrumb.next_member += 1;
+                        }
                         // Compute offsets and size of total type
                         let mut cur_offset = 0;
                         let mut max_alignment = 1;
                     let poly_type = self.lookup.get_mut(&breadcrumb.definition_id).unwrap();
                     let definition = poly_type.definition.as_struct_mut();
                     let mono_type = &mut definition.monomorphs[breadcrumb.monomorph_idx];
                         let mono_info = self.mono_lookup.get_mut(breadcrumb.monomorph_idx);
                         let mono_type = mono_info.variant.as_struct_mut();
                         let mut size_alignment_idx = breadcrumb.first_size_alignment_idx;
                         for field in &mut mono_type.fields {
                             let (size, alignment) = self.size_alignment_stack[size_alignment_idx];
                             field.size = size;
                             field.alignment = alignment;
                             size_alignment_idx += 1;
                             align_offset_to(&mut cur_offset, alignment);
                             field.offset = cur_offset;
                             cur_offset += size;
                             max_alignment = max_alignment.max(alignment);
+                        }
                     mono_type.size = cur_offset;
                     mono_type.alignment = max_alignment;
                         mono_info.size = cur_offset;
                         mono_info.alignment = max_alignment;
                         self.size_alignment_stack.truncate(breadcrumb.first_size_alignment_idx);
                     },
                     DTV::Function(_) | DTV::Component(_) => {
                         unreachable!();
+                    }
+                }
+            }
             // If here, then we completely layed out the current type. So move
             // to the next breadcrumb
             self.memory_layout_breadcrumbs.pop();
+        }
         debug_assert!(self.size_alignment_stack.is_empty());
         // If here then all types have been layed out. What remains is to
         // compute the sizes/alignment/offsets of the heap variants of the
         // unions we have encountered.
         for entry in &self.encountered_types {
             if !entry.is_union {
                 continue;
+            }
             // First pass, use buffer to store size/alignment to prevent
             // borrowing issues.
             let poly_type = self.lookup.get(&entry.definition_id).unwrap();
             let definition = poly_type.definition.as_union();
             let mono_type = &definition.monomorphs[entry.monomorph_idx];
             let mono_type = self.mono_lookup.get(entry.monomorph_idx).variant.as_union();
             for variant in &mono_type.variants {
                 if !variant.lives_on_heap {
                     continue;
+                }
                 debug_assert!(!variant.embedded.is_empty());
                 for embedded in &variant.embedded {
                     match self.get_memory_layout_or_breadcrumb(arch, &embedded.concrete_type.parts) {
                         MemoryLayoutResult::TypeExists(size, alignment) => {
                             self.size_alignment_stack.push((size, alignment));
                         },
                         _ => unreachable!(),
+                    }
+                }
+            }
             // Second pass, apply the size/alignment values in our buffer
             let poly_type = self.lookup.get_mut(&entry.definition_id).unwrap();
             let definition = poly_type.definition.as_union_mut();
             let mono_type = &mut definition.monomorphs[entry.monomorph_idx];
             let mono_type = self.mono_lookup.get_mut(entry.monomorph_idx).variant.as_union_mut();
             let mut max_size = 0;
             let mut max_alignment = 1;
             let mut size_alignment_idx = 0;
             for variant in &mut mono_type.variants {
                 if !variant.lives_on_heap {
                     continue;
+                }
                 let mut variant_offset = 0;
                 let mut variant_alignment = 1;
                 for embedded in &mut variant.embedded {
                     let (size, alignment) = self.size_alignment_stack[size_alignment_idx];
                     embedded.size = size;
                     embedded.alignment = alignment;
                     size_alignment_idx += 1;
                     align_offset_to(&mut variant_offset, alignment);
                     embedded.alignment = variant_offset;
                     variant_offset += size;
                     variant_alignment = variant_alignment.max(alignment);
+                }
                 max_size = max_size.max(variant_offset);
                 max_alignment = max_alignment.max(variant_alignment);
+            }
             if max_size != 0 {
                 // At least one entry lives on the heap
                 mono_type.heap_size = max_size;
                 mono_type.heap_alignment = max_alignment;
+            }
+        }
         // And now, we're actually, properly, done
         self.encountered_types.clear();
+    }
     /// Attempts to compute size/alignment for the provided type. Note that this
     /// is called *after* type loops have been succesfully resolved. Hence we
     /// may assume that all monomorph entries exist, but we may not assume that
     /// those entries already have their size/alignment computed.
     fn get_memory_layout_or_breadcrumb(&self, arch: &TargetArch, parts: &[ConcreteTypePart]) -> MemoryLayoutResult {
         use ConcreteTypePart as CTP;
         // Before we do any fancy shenanigans, we need to check if the concrete
         // type actually requires laying out memory.
         debug_assert!(!parts.is_empty());
         let (builtin_size, builtin_alignment) = match parts[0] {
             CTP::Void   => (0, 1),
             CTP::Message => arch.array_size_alignment,
             CTP::Bool   => (1, 1),
             CTP::UInt8  => (1, 1),
             CTP::UInt16 => (2, 2),
             CTP::UInt32 => (4, 4),
             CTP::UInt64 => (8, 8),
             CTP::SInt8  => (1, 1),
             CTP::SInt16 => (2, 2),
             CTP::SInt32 => (4, 4),
             CTP::SInt64 => (8, 8),
             CTP::Character => (4, 4),
             CTP::String => arch.string_size_alignment,
             CTP::Array => arch.array_size_alignment,
             CTP::Slice => arch.array_size_alignment,
             CTP::Input => arch.port_size_alignment,
             CTP::Output => arch.port_size_alignment,
             CTP::Tuple(num_embedded) => {
                 if num_embedded == 0 {
                     (0, 1)
             CTP::Tuple(_) => {
                 let mono_index = self.mono_lookup.get_monomorph_index(parts, &[]).unwrap();
                 if let Some((size, alignment)) = self.mono_lookup.get_monomorph_size_alignment(mono_index) {
                     return MemoryLayoutResult::TypeExists(size, alignment);
                 } else {
                     // TODO: This is a bit hacky: structs and unions are neatly
                     //  layed out element by element using the breadcrumbs, but
                     //  here we do special tuple checking. Tuples should be able
                     //  to get their own breadcrumbs for resolving (and storage
                     //  in the type table!)
                     debug_assert!(num_embedded > 1);
                     let mut total_size = 0;
                     let mut total_alignment = 1;
                     for embedded in ConcreteTypeIter::new(parts, 0) {
                         match self.get_memory_layout_or_breadcrumb(arch, embedded) {
                             MemoryLayoutResult::PushBreadcrumb(new_breadcrumb) => {
                                 return MemoryLayoutResult::PushBreadcrumb(new_breadcrumb);
                             },
                             MemoryLayoutResult::TypeExists(embedded_size, embedded_alignment) => {
                                 align_offset_to(&mut total_size, embedded_alignment);
                                 total_size += embedded_size;
                                 total_alignment = total_alignment.max(embedded_alignment);
+                            }
+                        }
+                    }
                     (total_size, total_alignment)
                     return MemoryLayoutResult::PushBreadcrumb(MemoryBreadcrumb{
                         definition_id: DefinitionId::new_invalid(),
                         monomorph_idx: mono_index,
                         next_member: 0,
                         next_embedded: 0,
                         first_size_alignment_idx: self.size_alignment_stack.len(),
                     })
+                }
             },
             CTP::Instance(definition_id, _) => {
                 // Retrieve entry and the specific monomorph index by applying
                 // the full concrete type.
                 let entry = self.lookup.get(&definition_id).unwrap();
                 let monomorph_idx = entry.get_monomorph_index(parts).unwrap();
                 let entry = self.type_lookup.get(&definition_id).unwrap();
                 let mono_index = self.mono_lookup.get_monomorph_index(parts, &entry.poly_vars).unwrap();
                 // Check if this monomorph has its size and alignment layed out,
                 // and if so: return it.
                 if let Some((size, alignment)) = entry.get_monomorph_size_alignment(monomorph_idx) {
                     // Type has been layed out in memory
                 if let Some((size, alignment)) = self.mono_lookup.get_monomorph_size_alignment(mono_index) {
                     return MemoryLayoutResult::TypeExists(size, alignment);
                 } else {
                     return MemoryLayoutResult::PushBreadcrumb(MemoryBreadcrumb{
                         definition_id,
                         monomorph_idx,
+                        monomorph_idx: mono_index,
                         next_member: 0,
                         next_embedded: 0,
                         first_size_alignment_idx: self.size_alignment_stack.len(),
                     });
+                }
             },
             CTP::Function(_, _) | CTP::Component(_, _) => {
                 todo!("storage for 'function pointers'");
+            }
         };
         return MemoryLayoutResult::TypeExists(builtin_size, builtin_alignment);
+    }
     /// Returns tag concrete type (always a builtin integer type), the size of
     /// that type in bytes (and implicitly, its alignment)
     fn variant_tag_type_from_values(min_val: i64, max_val: i64) -> (ConcreteType, usize) {
         debug_assert!(min_val <= max_val);
         let (part, size) = if min_val >= 0 {
             // Can be an unsigned integer
             if max_val <= (u8::MAX as i64) {
                 (ConcreteTypePart::UInt8, 1)
             } else if max_val <= (u16::MAX as i64) {
                 (ConcreteTypePart::UInt16, 2)
             } else if max_val <= (u32::MAX as i64) {
                 (ConcreteTypePart::UInt32, 4)
             } else {
                 (ConcreteTypePart::UInt64, 8)
+            }
         } else {
             // Must be a signed integer
             if min_val >= (i8::MIN as i64) && max_val <= (i8::MAX as i64) {
                 (ConcreteTypePart::SInt8, 1)
             } else if min_val >= (i16::MIN as i64) && max_val <= (i16::MAX as i64) {
                 (ConcreteTypePart::SInt16, 2)
             } else if min_val >= (i32::MIN as i64) && max_val <= (i32::MAX as i64) {
                 (ConcreteTypePart::SInt32, 4)
             } else {
                 (ConcreteTypePart::SInt64, 8)
+            }
         };
         return (ConcreteType{ parts: vec![part] }, size);
+    }
     //--------------------------------------------------------------------------
     // Small utilities
     //--------------------------------------------------------------------------
     fn create_polymorphic_variables(variables: &[Identifier]) -> Vec<PolymorphicVariable> {
         let mut result = Vec::with_capacity(variables.len());
         for variable in variables.iter() {
             result.push(PolymorphicVariable{ identifier: variable.clone(), is_in_use: false });
+        }
         result
+    }
     fn mark_used_polymorphic_variables(poly_vars: &mut Vec<PolymorphicVariable>, parser_type: &ParserType) {
         for element in &parser_type.elements {
             if let ParserTypeVariant::PolymorphicArgument(_, idx) = &element.variant {
                 poly_vars[*idx as usize].is_in_use = true;
+            }
+        }
+    }
+}
 #[inline]
 fn align_offset_to(offset: &mut usize, alignment: usize) {
     debug_assert!(alignment > 0);
     let alignment_min_1 = alignment - 1;
     *offset += alignment_min_1;
     *offset &= !(alignment_min_1);
+}
 #[inline]
 fn get_concrete_type_definition(concrete: &ConcreteType) -> DefinitionId {
     if let ConcreteTypePart::Instance(definition_id, _) = concrete.parts[0] {
         return definition_id;
     } else {
         debug_assert!(false, "passed {:?} to the type table", concrete);
         return DefinitionId::new_invalid()
+    }
+}
@@ \ No newline at end of file @@

src/protocol/tests/parser_monomorphs.rs

➞

Show inline comments

 /// parser_monomorphs.rs
 ///
 /// Simple tests to make sure that all of the appropriate monomorphs are
 /// instantiated
 use super::*;
 #[test]
 fn test_struct_monomorphs() {
     Tester::new_single_source_expect_ok(
         "no polymorph",
         "struct Integer{ s32 field }"
     ).for_struct("Integer", |s| { s
         .assert_num_monomorphs(1)
         .assert_has_monomorph("Integer");
     });
     Tester::new_single_source_expect_ok(
         "single polymorph",
+        "
         struct Number<T>{ T number }
         func instantiator() -> s32 {
             auto a = Number<s8>{ number: 0 };
             auto b = Number<s8>{ number: 1 };
             auto c = Number<s32>{ number: 2 };
             auto d = Number<s64>{ number: 3 };
             auto e = Number<Number<s16>>{ number: Number{ number: 4 }};
             return 0;
+        }
+        "
     ).for_struct("Number", |s| { s
         .assert_has_monomorph("Number<s8>")
         .assert_has_monomorph("Number<s16>")
         .assert_has_monomorph("Number<s32>")
         .assert_has_monomorph("Number<s64>")
         .assert_has_monomorph("Number<Number<s16>>")
         .assert_num_monomorphs(5);
     }).for_function("instantiator", |f| { f
         .for_variable("a", |v| {v.assert_concrete_type("Number<s8>");} )
         .for_variable("e", |v| {v.assert_concrete_type("Number<Number<s16>>");} );
     });
+}
 #[test]
 fn test_enum_monomorphs() {
     Tester::new_single_source_expect_ok(
         "no polymorph",
+        "
         enum Answer{ Yes, No }
         func do_it() -> s32 { auto a = Answer::Yes; return 0; }
+        "
     ).for_enum("Answer", |e| { e
         .assert_num_monomorphs(1)
         .assert_has_monomorph("Answer");
         .assert_has_monomorph("Answer")
         .assert_size_alignment("Answer", 1, 1);
     });
     // Note for reader: because the enum doesn't actually use the polymorphic
     // variable, we expect to have 1 monomorph: the type only has to be laid
     // out once.
     Tester::new_single_source_expect_ok(
         "single polymorph",
+        "
         enum Answer<T> { Yes, No }
         func instantiator() -> s32 {
             auto a = Answer<s8>::Yes;
             auto b = Answer<s8>::No;
             auto c = Answer<s32>::Yes;
             auto d = Answer<Answer<Answer<s64>>>::No;
             return 0;
+        }
+        "
     ).for_enum("Answer", |e| { e
         .assert_num_monomorphs(1)
         .assert_has_monomorph("Answer<s8>");
     });
+}
 #[test]
 fn test_union_monomorphs() {
     Tester::new_single_source_expect_ok(
         "no polymorph",
+        "
         union Trinary { Undefined, Value(bool) }
         func do_it() -> s32 { auto a = Trinary::Value(true); return 0; }
+        "
     ).for_union("Trinary", |e| { e
         .assert_num_monomorphs(1)
         .assert_has_monomorph("Trinary");
     });
     Tester::new_single_source_expect_ok(
         "polymorphs",
+        "
         union Result<T, E>{ Ok(T), Err(E) }
         func instantiator() -> s32 {
             s16 a_s16 = 5;
             auto a = Result<s8, bool>::Ok(0);
             auto b = Result<bool, s8>::Ok(true);
             auto c = Result<Result<s8, s32>, Result<s16, s64>>::Err(Result::Ok(5));
             auto d = Result<Result<s8, s32>, auto>::Err(Result<auto, s64>::Ok(a_s16));
             return 0;
+        }
+        "
     ).for_union("Result", |e| { e
         .assert_num_monomorphs(5)
         .assert_has_monomorph("Result<s8,bool>")
         .assert_has_monomorph("Result<bool,s8>")
         .assert_has_monomorph("Result<Result<s8,s32>,Result<s16,s64>>")
         .assert_has_monomorph("Result<s8,s32>")
         .assert_has_monomorph("Result<s16,s64>");
     }).for_function("instantiator", |f| { f
         .for_variable("d", |v| { v
             .assert_parser_type("auto")
             .assert_concrete_type("Result<Result<s8,s32>,Result<s16,s64>>");
         });
     });
+}
@@ \ No newline at end of file @@

src/protocol/tests/utils.rs

➞

Show inline comments

 use crate::collections::StringPool;
 use crate::protocol::{Module, ast::*, input_source::*, parser::{
     Parser,
     type_table::*,
     symbol_table::SymbolTable,
     token_parsing::*,
 }, eval::*, RunContext};
 // Carries information about the test into utility structures for builder-like
 // assertions
 #[derive(Clone, Copy)]
 struct TestCtx<'a> {
     test_name: &'a str,
     heap: &'a Heap,
     modules: &'a Vec<Module>,
     types: &'a TypeTable,
     symbols: &'a SymbolTable,
+}
 //------------------------------------------------------------------------------
 // Interface for parsing and compiling
 //------------------------------------------------------------------------------
 pub(crate) struct Tester {
     test_name: String,
     sources: Vec<String>
+}
 impl Tester {
     /// Constructs a new tester, allows adding multiple sources before compiling
     pub(crate) fn new<S: ToString>(test_name: S) -> Self {
         Self{
             test_name: test_name.to_string(),
             sources: Vec::new()
+        }
+    }
     /// Utility for quick tests that use a single source file and expect the
     /// compilation to succeed.
     pub(crate) fn new_single_source_expect_ok<T: ToString, S: ToString>(test_name: T, source: S) -> AstOkTester {
         Self::new(test_name)
             .with_source(source)
             .compile()
             .expect_ok()
+    }
     /// Utility for quick tests that use a single source file and expect the
     /// compilation to fail.
     pub(crate) fn new_single_source_expect_err<T: ToString, S: ToString>(test_name: T, source: S) -> AstErrTester {
         Self::new(test_name)
             .with_source(source)
             .compile()
             .expect_err()
+    }
     pub(crate) fn with_source<S: ToString>(mut self, source: S) -> Self {
         self.sources.push(source.to_string());
         self
+    }
     pub(crate) fn compile(self) -> AstTesterResult {
         let mut parser = Parser::new();
         for source in self.sources.into_iter() {
             let source = source.into_bytes();
             let input_source = InputSource::new(String::from(""), source);
             if let Err(err) = parser.feed(input_source) {
                 return AstTesterResult::Err(AstErrTester::new(self.test_name, err))
+            }
+        }
         if let Err(err) = parser.parse() {
             return AstTesterResult::Err(AstErrTester::new(self.test_name, err))
+        }
         AstTesterResult::Ok(AstOkTester::new(self.test_name, parser))
+    }
+}
 pub(crate) enum AstTesterResult {
     Ok(AstOkTester),
     Err(AstErrTester)
+}
 impl AstTesterResult {
     pub(crate) fn expect_ok(self) -> AstOkTester {
         match self {
             AstTesterResult::Ok(v) => v,
             AstTesterResult::Err(err) => {
                 let wrapped = ErrorTester{ test_name: &err.test_name, error: &err.error };
                 println!("DEBUG: Full error:\n{}", &err.error);
                 assert!(
                     false,
                     "[{}] Expected compilation to succeed, but it failed with {}",
                     err.test_name, wrapped.assert_postfix()
                 );
                 unreachable!();
+            }
+        }
+    }
     pub(crate) fn expect_err(self) -> AstErrTester {
         match self {
             AstTesterResult::Ok(ok) => {
                 assert!(false, "[{}] Expected compilation to fail, but it succeeded", ok.test_name);
                 unreachable!();
             },
             AstTesterResult::Err(err) => err,
+        }
+    }
+}
 //------------------------------------------------------------------------------
 // Interface for successful compilation
 //------------------------------------------------------------------------------
 #[allow(dead_code)]
 pub(crate) struct AstOkTester {
     test_name: String,
     modules: Vec<Module>,
     heap: Heap,
     symbols: SymbolTable,
     types: TypeTable,
     pool: StringPool, // This is stored because if we drop it on the floor, we lose all our `StringRef<'static>`s
+}
 impl AstOkTester {
     fn new(test_name: String, parser: Parser) -> Self {
         Self {
             test_name,
             modules: parser.modules.into_iter().map(|module| Module{
                 source: module.source,
                 root_id: module.root_id,
                 name: module.name.map(|(_, name)| name)
             }).collect(),
             heap: parser.heap,
             symbols: parser.symbol_table,
             types: parser.type_table,
             pool: parser.string_pool,
+        }
+    }
     pub(crate) fn for_struct<F: Fn(StructTester)>(self, name: &str, f: F) -> Self {
         let mut found = false;
         for definition in self.heap.definitions.iter() {
             if let Definition::Struct(ast_definition) = definition {
                 if ast_definition.identifier.value.as_str() != name {
                     continue;
+                }
                 // Found struct with the same name
                 let definition_id = ast_definition.this.upcast();
                 let type_entry = self.types.get_base_definition(&definition_id).unwrap();
                 let type_definition = type_entry.definition.as_struct();
                 let tester = StructTester::new(self.ctx(), ast_definition, type_definition);
                 f(tester);
                 found = true;
                 break
+            }
+        }
         assert!(
             found, "[{}] Failed to find definition for struct '{}'",
             self.test_name, name
         );
         self
+    }
     pub(crate) fn for_enum<F: Fn(EnumTester)>(self, name: &str, f: F) -> Self {
         let mut found = false;
         for definition in self.heap.definitions.iter() {
             if let Definition::Enum(definition) = definition {
                 if definition.identifier.value.as_str() != name {
                     continue;
+                }
                 // Found enum with the same name
                 let tester = EnumTester::new(self.ctx(), definition);
                 f(tester);
                 found = true;
                 break;
+            }
+        }
         assert!(
             found, "[{}] Failed to find definition for enum '{}'",
             self.test_name, name
         );
         self
+    }
     pub(crate) fn for_union<F: Fn(UnionTester)>(self, name: &str, f: F) -> Self {
         let mut found = false;
         for definition in self.heap.definitions.iter() {
             if let Definition::Union(definition) = definition {
                 if definition.identifier.value.as_str() != name {
                     continue;
+                }
                 // Found union with the same name
                 let definition_id = definition.this.upcast();
                 let base_type = self.types.get_base_definition(&definition_id).unwrap();
                 let tester = UnionTester::new(self.ctx(), definition, &base_type.definition.as_union());
                 f(tester);
                 found = true;
                 break;
+            }
+        }
         assert!(
             found, "[{}] Failed to find definition for union '{}'",
             self.test_name, name
         );
         self
+    }
     pub(crate) fn for_function<F: FnOnce(FunctionTester)>(self, name: &str, f: F) -> Self {
         let mut found = false;
         for definition in self.heap.definitions.iter() {
             if let Definition::Function(definition) = definition {
                 if definition.identifier.value.as_str() != name {
                     continue;
+                }
                 // Found function
                 let tester = FunctionTester::new(self.ctx(), definition);
                 f(tester);
                 found = true;
                 break;
+            }
+        }
         if found { return self }
         assert!(
             false, "[{}] failed to find definition for function '{}'",
             self.test_name, name
         );
         unreachable!();
+    }
     fn ctx(&self) -> TestCtx {
         TestCtx{
             test_name: &self.test_name,
             modules: &self.modules,
             heap: &self.heap,
             types: &self.types,
             symbols: &self.symbols,
+        }
+    }
+}
 //------------------------------------------------------------------------------
 // Utilities for successful compilation
 //------------------------------------------------------------------------------
 pub(crate) struct StructTester<'a> {
     ctx: TestCtx<'a>,
     ast_def: &'a StructDefinition,
     type_def: &'a StructType,
+}
 impl<'a> StructTester<'a> {
     fn new(ctx: TestCtx<'a>, ast_def: &'a StructDefinition, type_def: &'a StructType) -> Self {
         Self{ ctx, ast_def, type_def }
+    }
     pub(crate) fn assert_num_fields(self, num: usize) -> Self {
         assert_eq!(
             num, self.ast_def.fields.len(),
             "[{}] Expected {} struct fields, but found {} for {}",
             self.ctx.test_name, num, self.ast_def.fields.len(), self.assert_postfix()
         );
         self
+    }
     pub(crate) fn assert_num_monomorphs(self, num: usize) -> Self {
         let (is_equal, num_encountered) = has_equal_num_monomorphs(self.ctx, num, self.ast_def.this.upcast());
         assert!(
             is_equal, "[{}] Expected {} monomorphs, but got {} for {}",
             self.ctx.test_name, num, num_encountered, self.assert_postfix()
         );
         self
+    }
     pub(crate) fn assert_has_monomorph(self, serialized_monomorph: &str) -> Self {
         let (has_monomorph, serialized) = has_monomorph(self.ctx, self.ast_def.this.upcast(), serialized_monomorph);
         assert!(
             has_monomorph.is_some(), "[{}] Expected to find monomorph {}, but got {} for {}",
             self.ctx.test_name, serialized_monomorph, &serialized, self.assert_postfix()
         );
         self
+    }
     pub(crate) fn assert_size_alignment(mut self, monomorph: &str, size: usize, alignment: usize) -> Self {
         self = self.assert_has_monomorph(monomorph);
         let (mono_idx, _) = has_monomorph(self.ctx, self.ast_def.this.upcast(), monomorph);
         let mono_idx = mono_idx.unwrap();
         let mono = self.ctx.types.get_monomorph(mono_idx);
         let mono = &self.type_def.monomorphs[mono_idx];
         assert!(
             mono.size == size && mono.alignment == alignment,
             "[{}] Expected (size,alignment) of ({}, {}), but got ({}, {}) for {}",
             self.ctx.test_name, size, alignment, mono.size, mono.alignment, self.assert_postfix()
         );
         self
+    }
     pub(crate) fn for_field<F: Fn(StructFieldTester)>(self, name: &str, f: F) -> Self {
         // Find field with specified name
         for field in &self.ast_def.fields {
             if field.field.value.as_str() == name {
                 let tester = StructFieldTester::new(self.ctx, field);
                 f(tester);
                 return self;
+            }
+        }
         assert!(
             false, "[{}] Could not find struct field '{}' for {}",
             self.ctx.test_name, name, self.assert_postfix()
         );
         unreachable!();
+    }
     fn assert_postfix(&self) -> String {
         let mut v = String::new();
         v.push_str("Struct{ name: ");
         v.push_str(self.ast_def.identifier.value.as_str());
         v.push_str(", fields: [");
         for (field_idx, field) in self.ast_def.fields.iter().enumerate() {
             if field_idx != 0 { v.push_str(", "); }
             v.push_str(field.field.value.as_str());
+        }
         v.push_str("] }");
+        v
+    }
+}
 pub(crate) struct StructFieldTester<'a> {
     ctx: TestCtx<'a>,
     def: &'a StructFieldDefinition,
+}
 impl<'a> StructFieldTester<'a> {
     fn new(ctx: TestCtx<'a>, def: &'a StructFieldDefinition) -> Self {
         Self{ ctx, def }
+    }
     pub(crate) fn assert_parser_type(self, expected: &str) -> Self {
         let mut serialized_type = String::new();
         serialize_parser_type(&mut serialized_type, &self.ctx.heap, &self.def.parser_type);
         assert_eq!(
             expected, &serialized_type,
             "[{}] Expected type '{}', but got '{}' for {}",
             self.ctx.test_name, expected, &serialized_type, self.assert_postfix()
         );
         self
+    }
     fn assert_postfix(&self) -> String {
         let mut serialized_type = String::new();
         serialize_parser_type(&mut serialized_type, &self.ctx.heap, &self.def.parser_type);
         format!("StructField{{ name: {}, parser_type: {} }}", self.def.field.value.as_str(), serialized_type)
+    }
+}
 pub(crate) struct EnumTester<'a> {
     ctx: TestCtx<'a>,
     def: &'a EnumDefinition,
+}
 impl<'a> EnumTester<'a> {
     fn new(ctx: TestCtx<'a>, def: &'a EnumDefinition) -> Self {
         Self{ ctx, def }
+    }
     pub(crate) fn assert_num_variants(self, num: usize) -> Self {
         assert_eq!(
             num, self.def.variants.len(),
             "[{}] Expected {} enum variants, but found {} for {}",
             self.ctx.test_name, num, self.def.variants.len(), self.assert_postfix()
         );
         self
+    }
     pub(crate) fn assert_num_monomorphs(self, num: usize) -> Self {
         let (is_equal, num_encountered) = has_equal_num_monomorphs(self.ctx, num, self.def.this.upcast());
         assert!(
             is_equal, "[{}] Expected {} monomorphs, but got {} for {}",
             self.ctx.test_name, num, num_encountered, self.assert_postfix()
         );
         self
+    }
     pub(crate) fn assert_has_monomorph(self, serialized_monomorph: &str) -> Self {
         let (has_monomorph, serialized) = has_monomorph(self.ctx, self.def.this.upcast(), serialized_monomorph);
         assert!(
             has_monomorph.is_some(), "[{}] Expected to find monomorph {}, but got {} for {}",
             self.ctx.test_name, serialized_monomorph, serialized, self.assert_postfix()
         );
         self
+    }
     pub(crate) fn assert_size_alignment(mut self, serialized_monomorph: &str, size: usize, alignment: usize) -> Self {
         self = self.assert_has_monomorph(serialized_monomorph);
         let (has_monomorph, serialized) = has_monomorph(self.ctx, self.def.this.upcast(), serialized_monomorph);
         let mono_index = has_monomorph.unwrap();
         let mono = self.ctx.types.get_monomorph(mono_index);
         assert!(
             mono.size == size && mono.alignment == alignment,
             "[{}] Expected (size,alignment) of ({}, {}), but got ({}, {}) for {}",
             self.ctx.test_name, size, alignment, mono.size, mono.alignment, self.assert_postfix()
         );
         self
+    }
     pub(crate) fn assert_postfix(&self) -> String {
         let mut v = String::new();
         v.push_str("Enum{ name: ");
         v.push_str(self.def.identifier.value.as_str());
         v.push_str(", variants: [");
         for (variant_idx, variant) in self.def.variants.iter().enumerate() {
             if variant_idx != 0 { v.push_str(", "); }
             v.push_str(variant.identifier.value.as_str());
+        }
         v.push_str("] }");
+        v
+    }
+}
 pub(crate) struct UnionTester<'a> {
     ctx: TestCtx<'a>,
     ast_def: &'a UnionDefinition,
     type_def: &'a UnionType,
+}
 impl<'a> UnionTester<'a> {
     fn new(ctx: TestCtx<'a>, ast_def: &'a UnionDefinition, type_def: &'a UnionType) -> Self {
         Self{ ctx, ast_def, type_def }
+    }
     pub(crate) fn assert_num_variants(self, num: usize) -> Self {
         assert_eq!(
             num, self.ast_def.variants.len(),
             "[{}] Expected {} union variants, but found {} for {}",
             self.ctx.test_name, num, self.ast_def.variants.len(), self.assert_postfix()
         );
         self
+    }
     pub(crate) fn assert_num_monomorphs(self, num: usize) -> Self {
         let (is_equal, num_encountered) = has_equal_num_monomorphs(self.ctx, num, self.ast_def.this.upcast());
         assert!(
             is_equal, "[{}] Expected {} monomorphs, but got {} for {}",
             self.ctx.test_name, num, num_encountered, self.assert_postfix()
         );
         self
+    }
     pub(crate) fn assert_has_monomorph(self, serialized_monomorph: &str) -> Self {
         let (has_monomorph, serialized) = has_monomorph(self.ctx, self.ast_def.this.upcast(), serialized_monomorph);
         assert!(
             has_monomorph.is_some(), "[{}] Expected to find monomorph {}, but got {} for {}",
             self.ctx.test_name, serialized_monomorph, serialized, self.assert_postfix()
         );
         self
+    }
     pub(crate) fn assert_size_alignment(
         mut self, serialized_monomorph: &str,
         stack_size: usize, stack_alignment: usize, heap_size: usize, heap_alignment: usize
     ) -> Self {
         self = self.assert_has_monomorph(serialized_monomorph);
         let (mono_idx, _) = has_monomorph(self.ctx, self.ast_def.this.upcast(), serialized_monomorph);
         let mono_idx = mono_idx.unwrap();
         let mono = &self.type_def.monomorphs[mono_idx];
         let mono_base = self.ctx.types.get_monomorph(mono_idx);
         let mono_union = mono_base.variant.as_union();
         assert!(
             stack_size == mono.stack_size && stack_alignment == mono.stack_alignment &&
                 heap_size == mono.heap_size && heap_alignment == mono.heap_alignment,
             stack_size == mono_base.size && stack_alignment == mono_base.alignment &&
                 heap_size == mono_union.heap_size && heap_alignment == mono_union.heap_alignment,
             "[{}] Expected (stack | heap) (size, alignment) of ({}, {} | {}, {}), but got ({}, {} | {}, {}) for {}",
             self.ctx.test_name,
             stack_size, stack_alignment, heap_size, heap_alignment,
-            mono.stack_size, mono.stack_alignment, mono.heap_size, mono.heap_alignment,
+            mono_base.size, mono_base.alignment, mono_union.heap_size, mono_union.heap_alignment,
             self.assert_postfix()
         );
         self
+    }
     fn assert_postfix(&self) -> String {
         let mut v = String::new();
         v.push_str("Union{ name: ");
         v.push_str(self.ast_def.identifier.value.as_str());
         v.push_str(", variants: [");
         for (variant_idx, variant) in self.ast_def.variants.iter().enumerate() {
             if variant_idx != 0 { v.push_str(", "); }
             v.push_str(variant.identifier.value.as_str());
+        }
         v.push_str("] }");
+        v
+    }
+}
 pub(crate) struct FunctionTester<'a> {
     ctx: TestCtx<'a>,
     def: &'a FunctionDefinition,
+}
 impl<'a> FunctionTester<'a> {
     fn new(ctx: TestCtx<'a>, def: &'a FunctionDefinition) -> Self {
         Self{ ctx, def }
+    }
     pub(crate) fn for_variable<F: Fn(VariableTester)>(self, name: &str, f: F) -> Self {
         // Seek through the blocks in order to find the variable
         let wrapping_block_id = seek_stmt(
             self.ctx.heap, self.def.body.upcast(),
             &|stmt| {
                 if let Statement::Block(block) = stmt {
                     for local_id in &block.locals {
                         let var = &self.ctx.heap[*local_id];
                         if var.identifier.value.as_str() == name {
                             return true;
+                        }
+                    }
+                }
                 false
+            }
         );
         let mut found_local_id = None;
         if let Some(block_id) = wrapping_block_id {
             let block_stmt = self.ctx.heap[block_id].as_block();
             for local_id in &block_stmt.locals {
                 let var = &self.ctx.heap[*local_id];
                 if var.identifier.value.as_str() == name {
                     found_local_id = Some(*local_id);
+                }
+            }
+        }
         assert!(
             found_local_id.is_some(), "[{}] Failed to find variable '{}' in {}",
             self.ctx.test_name, name, self.assert_postfix()
         );
         let local = &self.ctx.heap[found_local_id.unwrap()];
         // Find an instance of the variable expression so we can determine its
         // type.
         let var_expr = seek_expr_in_stmt(
             self.ctx.heap, self.def.body.upcast(),
             &|expr| {
                 if let Expression::Variable(variable_expr) = expr {
                     if variable_expr.identifier.value.as_str() == name {
                         return true;
+                    }
+                }
                 false
+            }
         );
         assert!(
             var_expr.is_some(), "[{}] Failed to find variable expression of '{}' in {}",
             self.ctx.test_name, name, self.assert_postfix()
         );
         let var_expr = &self.ctx.heap[var_expr.unwrap()];
         // Construct tester and pass to tester function
         let tester = VariableTester::new(
             self.ctx, self.def.this.upcast(), local,
             var_expr.as_variable()
         );
         f(tester);
         self
+    }
     /// Finds a specific expression within a function. There are two matchers:
     /// one outer matcher (to find a rough indication of the expression) and an
     /// inner matcher to find the exact expression.
     ///
     /// The reason being that, for example, a function's body might be littered
     /// with addition symbols, so we first match on "some_var + some_other_var",
     /// and then match exactly on "+".
     pub(crate) fn for_expression_by_source<F: Fn(ExpressionTester)>(self, outer_match: &str, inner_match: &str, f: F) -> Self {
         // Seek the expression in the source code
         assert!(outer_match.contains(inner_match), "improper testing code");
         let module = seek_def_in_modules(
             &self.ctx.heap, &self.ctx.modules, self.def.this.upcast()
         ).unwrap();
         // Find the first occurrence of the expression after the definition of
         // the function, we'll check that it is included in the body later.
         let mut outer_match_idx = self.def.span.begin.offset as usize;
         while outer_match_idx < module.source.input.len() {
             if module.source.input[outer_match_idx..].starts_with(outer_match.as_bytes()) {
                 break;
+            }
             outer_match_idx += 1
+        }
         assert!(
             outer_match_idx < module.source.input.len(),
             "[{}] Failed to find '{}' within the source that contains {}",
             self.ctx.test_name, outer_match, self.assert_postfix()
         );
         let inner_match_idx = outer_match_idx + outer_match.find(inner_match).unwrap();
         // Use the inner match index to find the expression
         let expr_id = seek_expr_in_stmt(
             &self.ctx.heap, self.def.body.upcast(),
             &|expr| expr.operation_span().begin.offset as usize == inner_match_idx
         );
         assert!(
             expr_id.is_some(),
             "[{}] Failed to find '{}' within the source that contains {} \
             (note: expression was found, but not within the specified function",
             self.ctx.test_name, outer_match, self.assert_postfix()
         );
         let expr_id = expr_id.unwrap();
         // We have the expression, call the testing function
         let tester = ExpressionTester::new(
             self.ctx, self.def.this.upcast(), &self.ctx.heap[expr_id]
         );
         f(tester);
         self
+    }
     pub(crate) fn call_ok(self, expected_result: Option<Value>) -> Self {
         use crate::protocol::*;
         let (prompt, result) = self.eval_until_end();
         match result {
             Ok(_) => {
                 assert!(
                     prompt.store.stack.len() > 0, // note: stack never shrinks
                     "[{}] No value on stack after calling function for {}",
                     self.ctx.test_name, self.assert_postfix()
                 );
             },
             Err(err) => {
                 println!("DEBUG: Formatted evaluation error:\n{}", err);
                 assert!(
                     false,
                     "[{}] Expected call to succeed, but got {:?} for {}",
                     self.ctx.test_name, err, self.assert_postfix()
+                )
+            }
+        }
         if let Some(expected_result) = expected_result {
             debug_assert!(expected_result.get_heap_pos().is_none(), "comparing against heap thingamajigs is not yet implemented");
             assert!(
                 value::apply_equality_operator(&prompt.store, &prompt.store.stack[0], &expected_result),
                 "[{}] Result from call was {:?}, but expected {:?} for {}",
                 self.ctx.test_name, &prompt.store.stack[0], &expected_result, self.assert_postfix()
+            )
+        }
         self
+    }
     // Keeping this simple for now, will likely change
     pub(crate) fn call_err(self, expected_result: &str) -> Self {
         let (_, result) = self.eval_until_end();
         match result {
             Ok(_) => {
                 assert!(
                     false,
                     "[{}] Expected an error, but evaluation finished successfully for {}",
                     self.ctx.test_name, self.assert_postfix()
                 );
             },
             Err(err) => {
                 println!("DEBUG: Formatted evaluation error:\n{}", err);
                 debug_assert_eq!(err.statements.len(), 1);
                 assert!(
                     err.statements[0].message.contains(&expected_result),
                     "[{}] Expected error message to contain '{}', but it was '{}' for {}",
                     self.ctx.test_name, expected_result, err.statements[0].message, self.assert_postfix()
                 );
+            }
+        }
         self
+    }
     fn eval_until_end(&self) -> (Prompt, Result<EvalContinuation, EvalError>) {
         use crate::protocol::*;
         let mut prompt = Prompt::new(&self.ctx.types, &self.ctx.heap, self.def.this.upcast(), 0, ValueGroup::new_stack(Vec::new()));
         // Assuming the function is not polymorphic
         let definition_id = self.def.this.upcast();
         let func_type = [ConcreteTypePart::Function(definition_id, 0)];
         let mono_index = self.ctx.types.get_procedure_monomorph_index(&definition_id, &func_type).unwrap();
         let mut prompt = Prompt::new(&self.ctx.types, &self.ctx.heap, self.def.this.upcast(), mono_index, ValueGroup::new_stack(Vec::new()));
         let mut call_context = FakeRunContext{};
         loop {
             let result = prompt.step(&self.ctx.types, &self.ctx.heap, &self.ctx.modules, &mut call_context);
             match result {
                 Ok(EvalContinuation::Stepping) => {},
                 _ => return (prompt, result),
+            }
+        }
+    }
     fn assert_postfix(&self) -> String {
         format!("Function{{ name: {} }}", self.def.identifier.value.as_str())
+    }
+}
 pub(crate) struct VariableTester<'a> {
     ctx: TestCtx<'a>,
     definition_id: DefinitionId,
     variable: &'a Variable,
     var_expr: &'a VariableExpression,
+}
 impl<'a> VariableTester<'a> {
     fn new(
         ctx: TestCtx<'a>, definition_id: DefinitionId, variable: &'a Variable, var_expr: &'a VariableExpression
     ) -> Self {
         Self{ ctx, definition_id, variable, var_expr }
+    }
     pub(crate) fn assert_parser_type(self, expected: &str) -> Self {
         let mut serialized = String::new();
         serialize_parser_type(&mut serialized, self.ctx.heap, &self.variable.parser_type);
         assert_eq!(
             expected, &serialized,
             "[{}] Expected parser type '{}', but got '{}' for {}",
             self.ctx.test_name, expected, &serialized, self.assert_postfix()
         );
         self
+    }
     pub(crate) fn assert_concrete_type(self, expected: &str) -> Self {
         // Lookup concrete type in type table
-        let mono_data = self.ctx.types.get_procedure_expression_data(&self.definition_id, 0);
+        let mono_data = get_procedure_monomorph(&self.ctx.heap, &self.ctx.types, self.definition_id);
         let concrete_type = &mono_data.expr_data[self.var_expr.unique_id_in_definition as usize].expr_type;
         // Serialize and check
         let mut serialized = concrete_type.display_name(self.ctx.heap);
         assert_eq!(
             expected, &serialized,
             "[{}] Expected concrete type '{}', but got '{}' for {}",
             self.ctx.test_name, expected, &serialized, self.assert_postfix()
         );
         self
+    }
     fn assert_postfix(&self) -> String {
         format!("Variable{{ name: {} }}", self.variable.identifier.value.as_str())
+    }
+}
 pub(crate) struct ExpressionTester<'a> {
     ctx: TestCtx<'a>,
     definition_id: DefinitionId, // of the enclosing function/component
     expr: &'a Expression
+}
 impl<'a> ExpressionTester<'a> {
     fn new(
         ctx: TestCtx<'a>, definition_id: DefinitionId, expr: &'a Expression
     ) -> Self {
         Self{ ctx, definition_id, expr }
+    }
     pub(crate) fn assert_concrete_type(self, expected: &str) -> Self {
         // Lookup concrete type
-        let mono_data = self.ctx.types.get_procedure_expression_data(&self.definition_id, 0);
+        let mono_data = get_procedure_monomorph(&self.ctx.heap, &self.ctx.types, self.definition_id);
         let expr_index = self.expr.get_unique_id_in_definition();
         let concrete_type = &mono_data.expr_data[expr_index as usize].expr_type;
         // Serialize and check type
         let mut serialized = concrete_type.display_name(self.ctx.heap);
         assert_eq!(
             expected, &serialized,
             "[{}] Expected concrete type '{}', but got '{}' for {}",
             self.ctx.test_name, expected, &serialized, self.assert_postfix()
         );
         self
+    }
     fn assert_postfix(&self) -> String {
         format!(
             "Expression{{ debug: {:?} }}",
             self.expr
+        )
+    }
+}
 fn get_procedure_monomorph<'a>(heap: &Heap, types: &'a TypeTable, definition_id: DefinitionId) -> &'a ProcedureMonomorph {
     let ast_definition = &heap[definition_id];
     let func_type = if ast_definition.is_function() {
         [ConcreteTypePart::Function(definition_id, 0)]
     } else if ast_definition.is_component() {
         [ConcreteTypePart::Component(definition_id, 0)]
     } else {
         assert!(false);
         unreachable!()
     };
     let mono_index = types.get_procedure_monomorph_index(&definition_id, &func_type).unwrap();
     let mono_data = types.get_procedure_monomorph(mono_index);
     mono_data
+}
 //------------------------------------------------------------------------------
 // Interface for failed compilation
 //------------------------------------------------------------------------------
 pub(crate) struct AstErrTester {
     test_name: String,
     error: ParseError,
+}
 impl AstErrTester {
     fn new(test_name: String, error: ParseError) -> Self {
         Self{ test_name, error }
+    }
     pub(crate) fn error<F: Fn(ErrorTester)>(&self, f: F) {
         // Maybe multiple errors will be supported in the future
         let tester = ErrorTester{ test_name: &self.test_name, error: &self.error };
         f(tester)
+    }
+}
 //------------------------------------------------------------------------------
 // Utilities for failed compilation
 //------------------------------------------------------------------------------
 pub(crate) struct ErrorTester<'a> {
     test_name: &'a str,
     error: &'a ParseError,
+}
 impl<'a> ErrorTester<'a> {
     pub(crate) fn assert_num(self, num: usize) -> Self {
         assert_eq!(
             num, self.error.statements.len(),
             "[{}] expected error to consist of '{}' parts, but encountered '{}' for {}",
             self.test_name, num, self.error.statements.len(), self.assert_postfix()
         );
         self
+    }
     pub(crate) fn assert_ctx_has(self, idx: usize, msg: &str) -> Self {
         assert!(
             self.error.statements[idx].context.contains(msg),
             "[{}] expected error statement {}'s context to contain '{}' for {}",
             self.test_name, idx, msg, self.assert_postfix()
         );
         self
+    }
     pub(crate) fn assert_msg_has(self, idx: usize, msg: &str) -> Self {
         assert!(
             self.error.statements[idx].message.contains(msg),
             "[{}] expected error statement {}'s message to contain '{}' for {}",
             self.test_name, idx, msg, self.assert_postfix()
         );
         self
+    }
     /// Seeks the index of the pattern in the context message, then checks if
     /// the input position corresponds to that index.
     pub (crate) fn assert_occurs_at(self, idx: usize, pattern: &str) -> Self {
         let pos = self.error.statements[idx].context.find(pattern);
         assert!(
             pos.is_some(),
             "[{}] incorrect occurs_at: '{}' could not be found in the context for {}",
             self.test_name, pattern, self.assert_postfix()
         );
         let pos = pos.unwrap();
         let col = self.error.statements[idx].start_column as usize;
         assert_eq!(
             pos + 1, col,
             "[{}] Expected error to occur at column {}, but found it at {} for {}",
             self.test_name, pos + 1, col, self.assert_postfix()
         );
         self
+    }
     fn assert_postfix(&self) -> String {
         let mut v = String::new();
         v.push_str("error: [");
         for (idx, stmt) in self.error.statements.iter().enumerate() {
             if idx != 0 {
                 v.push_str(", ");
+            }
             v.push_str(&format!("{{ context: {}, message: {} }}", &stmt.context, stmt.message));
+        }
         v.push(']');
+        v
+    }
+}
 //------------------------------------------------------------------------------
 // Generic utilities
 //------------------------------------------------------------------------------
 fn has_equal_num_monomorphs(ctx: TestCtx, num: usize, definition_id: DefinitionId) -> (bool, usize) {
     use DefinedTypeVariant::*;
     // Again: inefficient, but its testing code
     let type_def = ctx.types.get_base_definition(&definition_id).unwrap();
     let num_on_type = match &type_def.definition {
         Struct(v) => v.monomorphs.len(),
         Enum(v) => v.monomorphs.len(),
         Union(v) => v.monomorphs.len(),
         Function(v) => v.monomorphs.len(),
         Component(v) => v.monomorphs.len(),
     let mut num_on_type = 0;
     for mono in &ctx.types.mono_lookup.monomorphs {
         match &mono.concrete_type.parts[0] {
             ConcreteTypePart::Instance(def_id, _) |
             ConcreteTypePart::Function(def_id, _) |
             ConcreteTypePart::Component(def_id, _) => {
                 if *def_id == definition_id {
                     num_on_type += 1;
+                }
             },
             _ => {},
         };
+    }
     (num_on_type == num, num_on_type)
+}
-fn has_monomorph(ctx: TestCtx, definition_id: DefinitionId, serialized_monomorph: &str) -> (Option<usize>, String) {
+fn has_monomorph(ctx: TestCtx, definition_id: DefinitionId, serialized_monomorph: &str) -> (Option<i32>, String) {
     use DefinedTypeVariant::*;
     let type_def = ctx.types.get_base_definition(&definition_id).unwrap();
     // Note: full_buffer is just for error reporting
     let mut full_buffer = String::new();
     let mut has_match = None;
     full_buffer.push('[');
     let mut append_to_full_buffer = |concrete_type: &ConcreteType, mono_idx: usize| {
         if full_buffer.len() != 1 {
             full_buffer.push_str(", ");
+        }
         full_buffer.push('"');
         let first_idx = full_buffer.len();
         full_buffer.push_str(concrete_type.display_name(ctx.heap).as_str());
         if &full_buffer[first_idx..] == serialized_monomorph {
             has_match = Some(mono_idx);
+            has_match = Some(mono_idx as i32);
+        }
         full_buffer.push('"');
     };
     match &type_def.definition {
         Enum(definition) => {
             for (mono_idx, mono) in definition.monomorphs.iter().enumerate() {
                 append_to_full_buffer(&mono.concrete_type, mono_idx);
+            }
         },
         Union(definition) => {
             for (mono_idx, mono) in definition.monomorphs.iter().enumerate() {
     // Bit wasteful, but this is (temporary?) testing code:
     for (mono_idx, mono) in ctx.types.mono_lookup.monomorphs.iter().enumerate() {
         append_to_full_buffer(&mono.concrete_type, mono_idx);
+    }
         },
         Struct(definition) => {
             for (mono_idx, mono) in definition.monomorphs.iter().enumerate() {
                 append_to_full_buffer(&mono.concrete_type, mono_idx);
+            }
         },
         Function(_) | Component(_) => {
             let monomorphs = type_def.definition.procedure_monomorphs();
             for (mono_idx, mono) in monomorphs.iter().enumerate() {
                 append_to_full_buffer(&mono.concrete_type, mono_idx);
+            }
+        }
+    }
     full_buffer.push(']');
     (has_match, full_buffer)
+}
 fn serialize_parser_type(buffer: &mut String, heap: &Heap, parser_type: &ParserType) {
     use ParserTypeVariant as PTV;
     fn serialize_variant(buffer: &mut String, heap: &Heap, parser_type: &ParserType, mut idx: usize) -> usize {
         match &parser_type.elements[idx].variant {
             PTV::Void => buffer.push_str("void"),
             PTV::InputOrOutput => {
                 buffer.push_str("portlike<");
                 idx = serialize_variant(buffer, heap, parser_type, idx + 1);
                 buffer.push('>');
             },
             PTV::ArrayLike => {
                 idx = serialize_variant(buffer, heap, parser_type, idx + 1);
                 buffer.push_str("[???]");
             },
             PTV::IntegerLike => buffer.push_str("integerlike"),
             PTV::Message => buffer.push_str(KW_TYPE_MESSAGE_STR),
             PTV::Bool => buffer.push_str(KW_TYPE_BOOL_STR),
             PTV::UInt8 => buffer.push_str(KW_TYPE_UINT8_STR),
             PTV::UInt16 => buffer.push_str(KW_TYPE_UINT16_STR),
             PTV::UInt32 => buffer.push_str(KW_TYPE_UINT32_STR),
             PTV::UInt64 => buffer.push_str(KW_TYPE_UINT64_STR),
             PTV::SInt8 => buffer.push_str(KW_TYPE_SINT8_STR),
             PTV::SInt16 => buffer.push_str(KW_TYPE_SINT16_STR),
             PTV::SInt32 => buffer.push_str(KW_TYPE_SINT32_STR),
             PTV::SInt64 => buffer.push_str(KW_TYPE_SINT64_STR),
             PTV::Character => buffer.push_str(KW_TYPE_CHAR_STR),
             PTV::String => buffer.push_str(KW_TYPE_STRING_STR),
             PTV::IntegerLiteral => buffer.push_str("int_literal"),
             PTV::Inferred => buffer.push_str(KW_TYPE_INFERRED_STR),
             PTV::Array => {
                 idx = serialize_variant(buffer, heap, parser_type, idx + 1);
                 buffer.push_str("[]");
             },
             PTV::Input => {
                 buffer.push_str(KW_TYPE_IN_PORT_STR);
                 buffer.push('<');
                 idx = serialize_variant(buffer, heap, parser_type, idx + 1);
                 buffer.push('>');
             },
             PTV::Output => {
                 buffer.push_str(KW_TYPE_OUT_PORT_STR);
                 buffer.push('<');
                 idx = serialize_variant(buffer, heap, parser_type, idx + 1);
                 buffer.push('>');
             },
             PTV::Tuple(num_embedded) => {
                 buffer.push('(');
                 for embedded_idx in 0..*num_embedded {
                     if embedded_idx != 0 {
                         buffer.push(',');
+                    }
                     idx = serialize_variant(buffer, heap, parser_type, idx + 1);
+                }
                 buffer.push(')');
             },
             PTV::PolymorphicArgument(definition_id, poly_idx) => {
                 let definition = &heap[*definition_id];
                 let poly_arg = &definition.poly_vars()[*poly_idx as usize];
                 buffer.push_str(poly_arg.value.as_str());
             },
             PTV::Definition(definition_id, num_embedded) => {
                 let definition = &heap[*definition_id];
                 buffer.push_str(definition.identifier().value.as_str());
                 let num_embedded = *num_embedded;
                 if num_embedded != 0 {
                     buffer.push('<');
                     for embedded_idx in 0..num_embedded {
                         if embedded_idx != 0 {
                             buffer.push(',');
+                        }
                         idx = serialize_variant(buffer, heap, parser_type, idx + 1);
+                    }
                     buffer.push('>');
+                }
+            }
+        }
         idx
+    }
     serialize_variant(buffer, heap, parser_type, 0);
+}
 fn seek_def_in_modules<'a>(heap: &Heap, modules: &'a [Module], def_id: DefinitionId) -> Option<&'a Module> {
     for module in modules {
         let root = &heap.protocol_descriptions[module.root_id];
         for definition in &root.definitions {
             if *definition == def_id {
                 return Some(module)
+            }
+        }
+    }
     None
+}
 fn seek_stmt<F: Fn(&Statement) -> bool>(heap: &Heap, start: StatementId, f: &F) -> Option<StatementId> {
     let stmt = &heap[start];
     if f(stmt) { return Some(start); }
     // This statement wasn't it, try to recurse
     let matched = match stmt {
         Statement::Block(block) => {
             for sub_id in &block.statements {
                 if let Some(id) = seek_stmt(heap, *sub_id, f) {
                     return Some(id);
+                }
+            }
             None
         },
         Statement::Labeled(stmt) => seek_stmt(heap, stmt.body, f),
         Statement::If(stmt) => {
             if let Some(id) = seek_stmt(heap, stmt.true_body.upcast(), f) {
                 return Some(id);
             } else if let Some(false_body) = stmt.false_body {
                 if let Some(id) = seek_stmt(heap, false_body.upcast(), f) {
                     return Some(id);
+                }
+            }
             None
         },
         Statement::While(stmt) => seek_stmt(heap, stmt.body.upcast(), f),
         Statement::Synchronous(stmt) => seek_stmt(heap, stmt.body.upcast(), f),
         _ => None
     };
     matched
+}
 fn seek_expr_in_expr<F: Fn(&Expression) -> bool>(heap: &Heap, start: ExpressionId, f: &F) -> Option<ExpressionId> {
     let expr = &heap[start];
     if f(expr) { return Some(start); }
     match expr {
         Expression::Assignment(expr) => {
             None
             .or_else(|| seek_expr_in_expr(heap, expr.left, f))
             .or_else(|| seek_expr_in_expr(heap, expr.right, f))
         },
         Expression::Binding(expr) => {
             None
             .or_else(|| seek_expr_in_expr(heap, expr.bound_to, f))
             .or_else(|| seek_expr_in_expr(heap, expr.bound_from, f))
+        }
         Expression::Conditional(expr) => {
             None
             .or_else(|| seek_expr_in_expr(heap, expr.test, f))
             .or_else(|| seek_expr_in_expr(heap, expr.true_expression, f))
             .or_else(|| seek_expr_in_expr(heap, expr.false_expression, f))
         },
         Expression::Binary(expr) => {
             None
             .or_else(|| seek_expr_in_expr(heap, expr.left, f))
             .or_else(|| seek_expr_in_expr(heap, expr.right, f))
         },
         Expression::Unary(expr) => {
             seek_expr_in_expr(heap, expr.expression, f)
         },
         Expression::Indexing(expr) => {
             None
             .or_else(|| seek_expr_in_expr(heap, expr.subject, f))
             .or_else(|| seek_expr_in_expr(heap, expr.index, f))
         },
         Expression::Slicing(expr) => {
             None
             .or_else(|| seek_expr_in_expr(heap, expr.subject, f))
             .or_else(|| seek_expr_in_expr(heap, expr.from_index, f))
             .or_else(|| seek_expr_in_expr(heap, expr.to_index, f))
         },
         Expression::Select(expr) => {
             seek_expr_in_expr(heap, expr.subject, f)
         },
         Expression::Literal(expr) => {
             if let Literal::Struct(lit) = &expr.value {
                 for field in &lit.fields {
                     if let Some(id) = seek_expr_in_expr(heap, field.value, f) {
                         return Some(id)
+                    }
+                }
             } else if let Literal::Array(elements) = &expr.value {
                 for element in elements {
                     if let Some(id) = seek_expr_in_expr(heap, *element, f) {
                         return Some(id)
+                    }
+                }
+            }
             None
         },
         Expression::Cast(expr) => {
             seek_expr_in_expr(heap, expr.subject, f)
+        }
         Expression::Call(expr) => {
             for arg in &expr.arguments {
                 if let Some(id) = seek_expr_in_expr(heap, *arg, f) {
                     return Some(id)
+                }
+            }
             None
         },
         Expression::Variable(_expr) => {
             None
+        }
+    }
+}
 fn seek_expr_in_stmt<F: Fn(&Expression) -> bool>(heap: &Heap, start: StatementId, f: &F) -> Option<ExpressionId> {
     let stmt = &heap[start];
     match stmt {
         Statement::Block(stmt) => {
             for stmt_id in &stmt.statements {
                 if let Some(id) = seek_expr_in_stmt(heap, *stmt_id, f) {
                     return Some(id)
+                }
+            }
             None
         },
         Statement::Labeled(stmt) => {
             seek_expr_in_stmt(heap, stmt.body, f)
         },
         Statement::If(stmt) => {
             None
             .or_else(|| seek_expr_in_expr(heap, stmt.test, f))
             .or_else(|| seek_expr_in_stmt(heap, stmt.true_body.upcast(), f))
             .or_else(|| if let Some(false_body) = stmt.false_body {
                 seek_expr_in_stmt(heap, false_body.upcast(), f)
             } else {
                 None
             })
         },
         Statement::While(stmt) => {
             None
             .or_else(|| seek_expr_in_expr(heap, stmt.test, f))
             .or_else(|| seek_expr_in_stmt(heap, stmt.body.upcast(), f))
         },
         Statement::Synchronous(stmt) => {
             seek_expr_in_stmt(heap, stmt.body.upcast(), f)
         },
         Statement::Return(stmt) => {
             for expr_id in &stmt.expressions {
                 if let Some(id) = seek_expr_in_expr(heap, *expr_id, f) {
                     return Some(id);
+                }
+            }
             None
         },
         Statement::New(stmt) => {
             seek_expr_in_expr(heap, stmt.expression.upcast(), f)
         },
         Statement::Expression(stmt) => {
             seek_expr_in_expr(heap, stmt.expression, f)
         },
         _ => None
+    }
+}
 struct FakeRunContext{}
 impl RunContext for FakeRunContext {
     fn performed_put(&mut self, _port: PortId) -> bool {
         unreachable!("'put' called in compiler testing code")
+    }
     fn performed_get(&mut self, _port: PortId) -> Option<ValueGroup> {
         unreachable!("'get' called in compiler testing code")
+    }
     fn fires(&mut self, _port: PortId) -> Option<Value> {
         unreachable!("'fires' called in compiler testing code")
+    }
     fn performed_fork(&mut self) -> Option<bool> {
         unreachable!("'fork' called in compiler testing code")
+    }
     fn created_channel(&mut self) -> Option<(Value, Value)> {
         unreachable!("channel created in compiler testing code")
+    }
+}
@@ \ No newline at end of file @@

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