CSY/reowolf Changeset - 10d2e43f1350 · Centrum Wiskunde & Informatica (CWI)

Changeset - 10d2e43f1350

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0 7 1

mh - 4 years ago 2021-05-20 11:19:56
contact@maxhenger.nl

WIP on poly rewrite

5 files changed:

src/collections/mod.rs

src/collections/sets.rs

src/protocol/ast.rs

src/protocol/parser/pass_definitions.rs

src/protocol/parser/pass_typing.rs

218

186

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0 comments (0 inline, 0 general)

src/collections/mod.rs

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 mod string_pool;
 mod scoped_buffer;
 mod sets;
 pub(crate) use string_pool::{StringPool, StringRef};
 pub(crate) use scoped_buffer::{ScopedBuffer, ScopedSection};
@@ \ No newline at end of file @@
 pub(crate) use scoped_buffer::{ScopedBuffer, ScopedSection};
 pub(crate) use sets::DequeSet;
@@ \ No newline at end of file @@

src/collections/sets.rs

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@@ new file 100644 @@
 use std::collections::VecDeque;
 /// Simple double ended queue that ensures that all elements are unique. Queue
 /// is not ordered.
 pub struct DequeSet<T: Eq> {
     inner: VecDeque<T>,
+}
 impl<T: Eq> DequeSet<T> {
     pub fn new() -> Self {
         Self{ inner: VecDeque::new() }
+    }
     #[inline]
     pub fn pop_front(&mut self) -> Option<T> {
         self.inner.pop_front()
+    }
     #[inline]
     pub fn pop_back(&mut self) -> Option<T> {
         self.inner.pop_back()
+    }
     #[inline]
     pub fn push_back(&mut self, to_push: T) {
         for element in self.inner.iter() {
             if *element == to_push {
                 return;
+            }
+        }
         self.inner.push_back(to_push);
+    }
     #[inline]
     pub fn push_front(&mut self, to_push: T) {
         for element in self.inner.iter() {
             if *element == to_push {
                 return;
+            }
+        }
         self.inner.push_front(to_push);
+    }
     #[inline]
     pub fn is_empty(&self) -> bool {
         self.inner.is_empty()
+    }
+}
@@ \ No newline at end of file @@

src/protocol/ast.rs

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@@ @@ -285,320 +285,316 @@ pub enum Import { @@
 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,
     // User-defined types
     PolymorphicArgument(DefinitionId, usize), // usize = index into polymorphic variables
     Definition(DefinitionId, usize), // usize = number of following subtypes
     PolymorphicArgument(DefinitionId, u32), // u32 = index into polymorphic variables
     Definition(DefinitionId, u32), // u32 = number of following subtypes
+}
 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) => *num,
+        }
+    }
+}
 #[derive(Debug, Clone)]
 pub struct ParserTypeElement {
     // TODO: @cleanup, do we ever need the span of a user-defined type after
     //  constructing it?
     pub full_span: InputSpan, // full span of type, including any polymorphic arguments
     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).
 #[derive(Debug, Clone)]
 pub struct ParserType {
     pub elements: Vec<ParserTypeElement>
+}
 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]);
+    }
+}
 /// Specifies whether the symbolic type points to an actual user-defined type,
 /// or whether it points to a polymorphic argument within the definition (e.g.
 /// a defined variable `T var` within a function `int func<T>()`
 #[derive(Debug, Clone)]
 pub enum SymbolicParserTypeVariant {
     Definition(DefinitionId),
     // TODO: figure out if I need the DefinitionId here
     PolyArg(DefinitionId, usize), // index of polyarg in the definition
+}
 /// ConcreteType is the representation of a type after resolving symbolic types
 /// and performing type inference
 #[derive(Debug, Clone, Copy, Eq, PartialEq)]
 pub enum ConcreteTypePart {
     // Markers for the use of polymorphic types within a procedure's body that
     // refer to polymorphic variables on the procedure's definition. Different
     // from markers in the `InferenceType`, these will not contain nested types.
     Marker(usize),
     // 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,
     // User defined type with any number of nested types
-    Instance(DefinitionId, usize),
+    Instance(DefinitionId, u32),
+}
 #[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 {
     pub(crate) fn has_marker(&self) -> bool {
         self.parts
             .iter()
             .any(|p| {
                 if let ConcreteTypePart::Marker(_) = p { true } else { false }
             })
+    }
+}
 // TODO: Remove at some point
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub enum PrimitiveType {
     Unassigned,
     Input,
     Output,
     Message,
     Boolean,
     Byte,
     Short,
     Int,
     Long,
+}
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub struct Type {
     pub primitive: PrimitiveType,
     pub array: bool,
+}
 #[allow(dead_code)]
 impl Type {
     pub const UNASSIGNED: Type = Type { primitive: PrimitiveType::Unassigned, array: false };
     pub const INPUT: Type = Type { primitive: PrimitiveType::Input, array: false };
     pub const OUTPUT: Type = Type { primitive: PrimitiveType::Output, array: false };
     pub const MESSAGE: Type = Type { primitive: PrimitiveType::Message, array: false };
     pub const BOOLEAN: Type = Type { primitive: PrimitiveType::Boolean, array: false };
     pub const BYTE: Type = Type { primitive: PrimitiveType::Byte, array: false };
     pub const SHORT: Type = Type { primitive: PrimitiveType::Short, array: false };
     pub const INT: Type = Type { primitive: PrimitiveType::Int, array: false };
     pub const LONG: Type = Type { primitive: PrimitiveType::Long, array: false };
     pub const INPUT_ARRAY: Type = Type { primitive: PrimitiveType::Input, array: true };
     pub const OUTPUT_ARRAY: Type = Type { primitive: PrimitiveType::Output, array: true };
     pub const MESSAGE_ARRAY: Type = Type { primitive: PrimitiveType::Message, array: true };
     pub const BOOLEAN_ARRAY: Type = Type { primitive: PrimitiveType::Boolean, array: true };
     pub const BYTE_ARRAY: Type = Type { primitive: PrimitiveType::Byte, array: true };
     pub const SHORT_ARRAY: Type = Type { primitive: PrimitiveType::Short, array: true };
     pub const INT_ARRAY: Type = Type { primitive: PrimitiveType::Int, array: true };
     pub const LONG_ARRAY: Type = Type { primitive: PrimitiveType::Long, array: true };
+}
 impl Display for Type {
     fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
         match &self.primitive {
             PrimitiveType::Unassigned => {
                 write!(f, "unassigned")?;
+            }
             PrimitiveType::Input => {
                 write!(f, "in")?;
+            }
             PrimitiveType::Output => {
                 write!(f, "out")?;
+            }
             PrimitiveType::Message => {
                 write!(f, "msg")?;
+            }
             PrimitiveType::Boolean => {
                 write!(f, "boolean")?;
+            }
             PrimitiveType::Byte => {
                 write!(f, "byte")?;
+            }
             PrimitiveType::Short => {
                 write!(f, "short")?;
+            }
             PrimitiveType::Int => {
                 write!(f, "int")?;
+            }
             PrimitiveType::Long => {
                 write!(f, "long")?;
+            }
@@ @@ -833,244 +829,251 @@ pub struct StructDefinition { @@
     pub this: StructDefinitionId,
     pub defined_in: RootId,
     // Phase 1: symbol scanning
     pub span: InputSpan,
     pub identifier: Identifier,
     pub poly_vars: Vec<Identifier>,
     // Phase 2: 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)]
 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,
     // Phase 1: symbol scanning
     pub span: InputSpan,
     pub identifier: Identifier,
     pub poly_vars: Vec<Identifier>,
     // Phase 2: 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 enum UnionVariantValue {
     None,
     Embedded(Vec<ParserType>),
+}
 #[derive(Debug, Clone)]
 pub struct UnionVariantDefinition {
     pub span: InputSpan,
     pub identifier: Identifier,
     pub value: UnionVariantValue,
+}
 #[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,
-    // Phase 1: symbol scanning
+    // Symbol scanning
     pub span: InputSpan,
     pub variant: ComponentVariant,
     pub identifier: Identifier,
     pub poly_vars: Vec<Identifier>,
-    // Phase 2: parsing
+    // 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()
             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,
-    // Phase 1: symbol scanning
+    // Symbol scanning
     pub builtin: bool,
     pub span: InputSpan,
     pub identifier: Identifier,
     pub poly_vars: Vec<Identifier>,
-    // Phase 2: parsing
+    // 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),
     Return(ReturnStatement),
     Goto(GotoStatement),
     New(NewStatement),
     Expression(ExpressionStatement),
+}
 impl Statement {
     pub fn is_block(&self) -> bool {
         match self {
             Statement::Block(_) => true,
             _ => false,
+        }
+    }
     pub fn as_block(&self) -> &BlockStatement {
         match self {
             Statement::Block(result) => result,
             _ => panic!("Unable to cast `Statement` to `BlockStatement`"),
+        }
+    }
     pub fn as_block_mut(&mut self) -> &mut 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_labeled(&self) -> &LabeledStatement {
         match self {
             Statement::Labeled(result) => result,
             _ => panic!("Unable to cast `Statement` to `LabeledStatement`"),
+        }
+    }
     pub fn as_labeled_mut(&mut self) -> &mut LabeledStatement {
         match self {
             Statement::Labeled(result) => result,
             _ => panic!("Unable to cast `Statement` to `LabeledStatement`"),
+        }
+    }
     pub fn as_if(&self) -> &IfStatement {
         match self {
             Statement::If(result) => result,
             _ => panic!("Unable to cast `Statement` to `IfStatement`"),
+        }
+    }
     pub fn as_if_mut(&mut self) -> &mut IfStatement {
         match self {
             Statement::If(result) => result,
             _ => panic!("Unable to cast 'Statement' to 'IfStatement'"),
+        }
+    }
     pub fn as_end_if(&self) -> &EndIfStatement {
         match self {
             Statement::EndIf(result) => result,
             _ => panic!("Unable to cast `Statement` to `EndIfStatement`"),
+        }
+    }
     pub fn is_while(&self) -> bool {
         match self {
             Statement::While(_) => true,
             _ => false,
+        }
+    }
     pub fn as_while(&self) -> &WhileStatement {
         match self {
             Statement::While(result) => result,
             _ => panic!("Unable to cast `Statement` to `WhileStatement`"),
+        }
@@ @@ -1508,405 +1511,432 @@ impl Expression { @@
             _ => panic!("Unable to cast `Expression` to `VariableExpression`"),
+        }
+    }
     pub fn as_variable_mut(&mut self) -> &mut VariableExpression {
         match self {
             Expression::Variable(result) => result,
             _ => panic!("Unable to cast `Expression` to `VariableExpression`"),
+        }
+    }
     pub fn span(&self) -> InputSpan {
         match self {
             Expression::Assignment(expr) => expr.span,
             Expression::Binding(expr) => expr.span,
             Expression::Conditional(expr) => expr.span,
             Expression::Binary(expr) => expr.span,
             Expression::Unary(expr) => expr.span,
             Expression::Indexing(expr) => expr.span,
             Expression::Slicing(expr) => expr.span,
             Expression::Select(expr) => expr.span,
             Expression::Literal(expr) => expr.span,
             Expression::Call(expr) => expr.span,
             Expression::Variable(expr) => expr.identifier.span,
+        }
+    }
     // TODO: @cleanup
     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::Call(expr) => &expr.parent,
             Expression::Variable(expr) => &expr.parent,
+        }
+    }
     // TODO: @cleanup
     pub fn parent_expr_id(&self) -> Option<ExpressionId> {
         if let ExpressionParent::Expression(id, _) = self.parent() {
             Some(*id)
         } else {
             None
+        }
+    }
     // TODO: @cleanup
     pub fn set_parent(&mut self, parent: ExpressionParent) {
         match self {
             Expression::Assignment(expr) => expr.parent = parent,
             Expression::Binding(expr) => expr.parent = parent,
             Expression::Conditional(expr) => expr.parent = parent,
             Expression::Binary(expr) => expr.parent = parent,
             Expression::Unary(expr) => expr.parent = parent,
             Expression::Indexing(expr) => expr.parent = parent,
             Expression::Slicing(expr) => expr.parent = parent,
             Expression::Select(expr) => expr.parent = parent,
             Expression::Literal(expr) => expr.parent = parent,
             Expression::Call(expr) => expr.parent = parent,
             Expression::Variable(expr) => expr.parent = parent,
+        }
+    }
     pub fn get_type(&self) -> &ConcreteType {
         match self {
             Expression::Assignment(expr) => &expr.concrete_type,
             Expression::Binding(expr) => &expr.concrete_type,
             Expression::Conditional(expr) => &expr.concrete_type,
             Expression::Binary(expr) => &expr.concrete_type,
             Expression::Unary(expr) => &expr.concrete_type,
             Expression::Indexing(expr) => &expr.concrete_type,
             Expression::Slicing(expr) => &expr.concrete_type,
             Expression::Select(expr) => &expr.concrete_type,
             Expression::Literal(expr) => &expr.concrete_type,
             Expression::Call(expr) => &expr.concrete_type,
             Expression::Variable(expr) => &expr.concrete_type,
+        }
+    }
     // TODO: @cleanup
     pub fn get_type_mut(&mut self) -> &mut ConcreteType {
         match self {
             Expression::Assignment(expr) => &mut expr.concrete_type,
             Expression::Binding(expr) => &mut expr.concrete_type,
             Expression::Conditional(expr) => &mut expr.concrete_type,
             Expression::Binary(expr) => &mut expr.concrete_type,
             Expression::Unary(expr) => &mut expr.concrete_type,
             Expression::Indexing(expr) => &mut expr.concrete_type,
             Expression::Slicing(expr) => &mut expr.concrete_type,
             Expression::Select(expr) => &mut expr.concrete_type,
             Expression::Literal(expr) => &mut expr.concrete_type,
             Expression::Call(expr) => &mut expr.concrete_type,
             Expression::Variable(expr) => &mut expr.concrete_type,
+        }
+    }
     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::Call(expr) => expr.unique_id_in_definition,
             Expression::Variable(expr) => expr.unique_id_in_definition,
+        }
+    }
+}
 #[derive(Debug, Clone, Copy)]
 pub enum AssignmentOperator {
     Set,
     Multiplied,
     Divided,
     Remained,
     Added,
     Subtracted,
     ShiftedLeft,
     ShiftedRight,
     BitwiseAnded,
     BitwiseXored,
     BitwiseOred,
+}
 #[derive(Debug, Clone)]
 pub struct AssignmentExpression {
     pub this: AssignmentExpressionId,
     // Parsing
     pub span: InputSpan, // of the operator
     pub left: ExpressionId,
     pub operation: AssignmentOperator,
     pub right: ExpressionId,
     // Validator/Linker
     pub parent: ExpressionParent,
     pub unique_id_in_definition: i32,
     // Typing
     pub concrete_type: ConcreteType,
+}
 #[derive(Debug, Clone)]
 pub struct BindingExpression {
     pub this: BindingExpressionId,
     // Parsing
     pub span: InputSpan,
     pub left: LiteralExpressionId,
     pub right: ExpressionId,
     // Validator/Linker
     pub parent: ExpressionParent,
     pub unique_id_in_definition: i32,
     // Typing
     pub concrete_type: ConcreteType,
+}
 #[derive(Debug, Clone)]
 pub struct ConditionalExpression {
     pub this: ConditionalExpressionId,
     // Parsing
     pub span: InputSpan, // of question mark operator
     pub test: ExpressionId,
     pub true_expression: ExpressionId,
     pub false_expression: ExpressionId,
     // Validator/Linking
     pub parent: ExpressionParent,
     pub unique_id_in_definition: i32,
     // Typing
     pub concrete_type: ConcreteType,
+}
 #[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 span: InputSpan, // of the operator
     pub left: ExpressionId,
     pub operation: BinaryOperator,
     pub right: ExpressionId,
     // Validator/Linker
     pub parent: ExpressionParent,
     pub unique_id_in_definition: i32,
     // Typing
     pub concrete_type: ConcreteType,
+}
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub enum UnaryOperator {
     Positive,
     Negative,
     BitwiseNot,
     LogicalNot,
     PreIncrement,
     PreDecrement,
     PostIncrement,
     PostDecrement,
+}
 #[derive(Debug, Clone)]
 pub struct UnaryExpression {
     pub this: UnaryExpressionId,
     // Parsing
     pub span: InputSpan, // of the operator
     pub operation: UnaryOperator,
     pub expression: ExpressionId,
     // Validator/Linker
     pub parent: ExpressionParent,
     pub unique_id_in_definition: i32,
     // Typing
     pub concrete_type: ConcreteType,
+}
 #[derive(Debug, Clone)]
 pub struct IndexingExpression {
     pub this: IndexingExpressionId,
     // Parsing
     pub span: InputSpan,
     pub subject: ExpressionId,
     pub index: ExpressionId,
     // Validator/Linker
     pub parent: ExpressionParent,
     pub unique_id_in_definition: i32,
     // Typing
     pub concrete_type: ConcreteType,
+}
 #[derive(Debug, Clone)]
 pub struct SlicingExpression {
     pub this: SlicingExpressionId,
     // Parsing
     pub span: InputSpan, // from '[' to ']';
     pub subject: ExpressionId,
     pub from_index: ExpressionId,
     pub to_index: ExpressionId,
     // Validator/Linker
     pub parent: ExpressionParent,
     pub unique_id_in_definition: i32,
     // Typing
     pub concrete_type: ConcreteType,
+}
 #[derive(Debug, Clone)]
 pub struct SelectExpression {
     pub this: SelectExpressionId,
     // Parsing
     pub span: InputSpan, // of the '.'
     pub subject: ExpressionId,
     pub field: Field,
     // Validator/Linker
     pub parent: ExpressionParent,
     pub unique_id_in_definition: i32,
     // Typing
     pub concrete_type: ConcreteType,
+}
 #[derive(Debug, Clone)]
 pub struct CallExpression {
     pub this: CallExpressionId,
     // Parsing
     pub span: InputSpan,
     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,
     // Typing
     pub concrete_type: ConcreteType, // of the return type
+}
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub enum Method {
     // Builtin
     Get,
     Put,
     Fires,
     Create,
     Length,
     Assert,
     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,
     // Typing
     pub concrete_type: ConcreteType,
+}
 #[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_struct_mut(&mut self) -> &mut 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 parent: ExpressionParent,
     pub unique_id_in_definition: i32,
     // Typing
     pub concrete_type: ConcreteType,
+}
@@ \ No newline at end of file @@

src/protocol/parser/pass_definitions.rs

➞

Show inline comments

 use crate::protocol::ast::*;
 use super::symbol_table::*;
 use super::{Module, ModuleCompilationPhase, PassCtx};
 use super::tokens::*;
 use super::token_parsing::*;
 use crate::protocol::input_source::{InputSource as InputSource, InputPosition as InputPosition, InputSpan, ParseError};
 use crate::collections::*;
 /// Parses all the tokenized definitions into actual AST nodes.
 pub(crate) struct PassDefinitions {
     // State
+    // State associated with the definition currently being processed
     cur_definition: DefinitionId,
     // Temporary buffers of various kinds
     buffer: String,
     struct_fields: ScopedBuffer<StructFieldDefinition>,
     enum_variants: ScopedBuffer<EnumVariantDefinition>,
     union_variants: ScopedBuffer<UnionVariantDefinition>,
     variables: ScopedBuffer<VariableId>,
     expressions: ScopedBuffer<ExpressionId>,
     statements: ScopedBuffer<StatementId>,
     parser_types: ScopedBuffer<ParserType>,
+}
 impl PassDefinitions {
     pub(crate) fn new() -> Self {
         Self{
             cur_definition: DefinitionId::new_invalid(),
             buffer: String::with_capacity(128),
             struct_fields: ScopedBuffer::new_reserved(128),
             enum_variants: ScopedBuffer::new_reserved(128),
             union_variants: ScopedBuffer::new_reserved(128),
             variables: ScopedBuffer::new_reserved(128),
             expressions: ScopedBuffer::new_reserved(128),
             statements: ScopedBuffer::new_reserved(128),
             parser_types: ScopedBuffer::new_reserved(128),
+        }
+    }
     pub(crate) fn parse(&mut self, modules: &mut [Module], module_idx: usize, ctx: &mut PassCtx) -> Result<(), ParseError> {
         let module = &modules[module_idx];
         let module_range = &module.tokens.ranges[0];
         debug_assert_eq!(module.phase, ModuleCompilationPhase::ImportsResolved);
         debug_assert_eq!(module_range.range_kind, TokenRangeKind::Module);
         // Although we only need to parse the definitions, we want to go through
         // code ranges as well such that we can throw errors if we get
         // unexpected tokens at the module level of the source.
         let mut range_idx = module_range.first_child_idx;
         loop {
             let range_idx_usize = range_idx as usize;
             let cur_range = &module.tokens.ranges[range_idx_usize];
             match cur_range.range_kind {
                 TokenRangeKind::Module => unreachable!(), // should not be reachable
                 TokenRangeKind::Pragma | TokenRangeKind::Import => {
                     // Already fully parsed, fall through and go to next range
                 },
                 TokenRangeKind::Definition | TokenRangeKind::Code => {
                     // Visit range even if it is a "code" range to provide
                     // proper error messages.
                     self.visit_range(modules, module_idx, ctx, range_idx_usize)?;
                 },
+            }
             if cur_range.next_sibling_idx == NO_SIBLING {
                 break;
             } else {
                 range_idx = cur_range.next_sibling_idx;
+            }
+        }
         modules[module_idx].phase = ModuleCompilationPhase::DefinitionsParsed;
         Ok(())
+    }
     fn visit_range(
         &mut self, modules: &[Module], module_idx: usize, ctx: &mut PassCtx, range_idx: usize
     ) -> Result<(), ParseError> {
         let module = &modules[module_idx];
         let cur_range = &module.tokens.ranges[range_idx];
         debug_assert!(cur_range.range_kind == TokenRangeKind::Definition || cur_range.range_kind == TokenRangeKind::Code);
         // Detect which definition we're parsing
         let mut iter = module.tokens.iter_range(cur_range);
         loop {
             let next = iter.next();
             if next.is_none() {
                 return Ok(())
+            }
             // Token was not None, so peek_ident returns None if not an ident
             let ident = peek_ident(&module.source, &mut iter);
             match ident {
                 Some(KW_STRUCT) => self.visit_struct_definition(module, &mut iter, ctx)?,
                 Some(KW_ENUM) => self.visit_enum_definition(module, &mut iter, ctx)?,
                 Some(KW_UNION) => self.visit_union_definition(module, &mut iter, ctx)?,
                 Some(KW_FUNCTION) => self.visit_function_definition(module, &mut iter, ctx)?,
                 Some(KW_PRIMITIVE) | Some(KW_COMPOSITE) => self.visit_component_definition(module, &mut iter, ctx)?,
                 _ => return Err(ParseError::new_error_str_at_pos(
                     &module.source, iter.last_valid_pos(),
                     "unexpected symbol, expected a keyword marking the start of a definition"
                 )),
+            }
+        }
+    }
@@ @@ -154,246 +154,248 @@ impl PassDefinitions { @@
         let (ident_text, _) = consume_ident(&module.source, iter)?;
         // Retrieve preallocated DefinitionId
         let module_scope = SymbolScope::Module(module.root_id);
         let definition_id = ctx.symbols.get_symbol_by_name_defined_in_scope(module_scope, ident_text)
             .unwrap().variant.as_definition().definition_id;
         self.cur_definition = definition_id;
         // Parse enum definition
         consume_polymorphic_vars_spilled(&module.source, iter, ctx)?;
         let mut enum_section = self.enum_variants.start_section();
         consume_comma_separated(
             TokenKind::OpenCurly, TokenKind::CloseCurly, &module.source, iter, ctx,
             |source, iter, ctx| {
                 let identifier = consume_ident_interned(source, iter, ctx)?;
                 let value = if iter.next() == Some(TokenKind::Equal) {
                     iter.consume();
                     let (variant_number, _) = consume_integer_literal(source, iter, &mut self.buffer)?;
                     EnumVariantValue::Integer(variant_number as i64) // TODO: @int
                 } else {
                     EnumVariantValue::None
                 };
                 Ok(EnumVariantDefinition{ identifier, value })
             },
             &mut enum_section, "an enum variant", "a list of enum variants", None
         )?;
         // Transfer to definition
         let enum_def = ctx.heap[definition_id].as_enum_mut();
         enum_def.variants = enum_section.into_vec();
         Ok(())
+    }
     fn visit_union_definition(
         &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
     ) -> Result<(), ParseError> {
         consume_exact_ident(&module.source, iter, KW_UNION)?;
         let (ident_text, _) = consume_ident(&module.source, iter)?;
         // Retrieve preallocated DefinitionId
         let module_scope = SymbolScope::Module(module.root_id);
         let definition_id = ctx.symbols.get_symbol_by_name_defined_in_scope(module_scope, ident_text)
             .unwrap().variant.as_definition().definition_id;
         self.cur_definition = definition_id;
         // Parse union definition
         consume_polymorphic_vars_spilled(&module.source, iter, ctx)?;
         let mut variants_section = self.union_variants.start_section();
         consume_comma_separated(
             TokenKind::OpenCurly, TokenKind::CloseCurly, &module.source, iter, ctx,
             |source, iter, ctx| {
                 let identifier = consume_ident_interned(source, iter, ctx)?;
                 let mut close_pos = identifier.span.end;
                 let mut types_section = self.parser_types.start_section();
                 let has_embedded = maybe_consume_comma_separated(
                     TokenKind::OpenParen, TokenKind::CloseParen, source, iter, ctx,
                     |source, iter, ctx| {
                         let poly_vars = ctx.heap[definition_id].poly_vars(); // TODO: @Cleanup, this is really ugly. But rust...
                         consume_parser_type(
                             source, iter, &ctx.symbols, &ctx.heap, poly_vars,
                             module_scope, definition_id, false, 0
+                        )
                     },
                     &mut types_section, "an embedded type", Some(&mut close_pos)
                 )?;
                 let value = if has_embedded {
                     UnionVariantValue::Embedded(types_section.into_vec())
                 } else {
                     types_section.forget();
                     UnionVariantValue::None
                 };
                 Ok(UnionVariantDefinition{
                     span: InputSpan::from_positions(identifier.span.begin, close_pos),
                     identifier,
                     value
                 })
             },
             &mut variants_section, "a union variant", "a list of union variants", None
         )?;
         // Transfer to AST
         let union_def = ctx.heap[definition_id].as_union_mut();
         union_def.variants = variants_section.into_vec();
         Ok(())
+    }
     fn visit_function_definition(
         &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
     ) -> Result<(), ParseError> {
         // Retrieve function name
         consume_exact_ident(&module.source, iter, KW_FUNCTION)?;
         let (ident_text, _) = consume_ident(&module.source, iter)?;
         // Retrieve preallocated DefinitionId
         let module_scope = SymbolScope::Module(module.root_id);
         let definition_id = ctx.symbols.get_symbol_by_name_defined_in_scope(module_scope, ident_text)
             .unwrap().variant.as_definition().definition_id;
         self.cur_definition = definition_id;
         consume_polymorphic_vars_spilled(&module.source, iter, ctx)?;
         // Parse function's argument list
         let mut parameter_section = self.variables.start_section();
         consume_parameter_list(
             &module.source, iter, ctx, &mut parameter_section, module_scope, definition_id
         )?;
         let parameters = parameter_section.into_vec();
         // Consume return types
         consume_token(&module.source, iter, TokenKind::ArrowRight)?;
         let mut return_types = self.parser_types.start_section();
         let mut open_curly_pos = iter.last_valid_pos(); // bogus value
         consume_comma_separated_until(
             TokenKind::OpenCurly, &module.source, iter, ctx,
             |source, iter, ctx| {
                 let poly_vars = ctx.heap[definition_id].poly_vars(); // TODO: @Cleanup, this is really ugly. But rust...
                 consume_parser_type(source, iter, &ctx.symbols, &ctx.heap, poly_vars, module_scope, definition_id, false, 0)
             },
             &mut return_types, "a return type", Some(&mut open_curly_pos)
         )?;
         let return_types = return_types.into_vec();
         // TODO: @ReturnValues
         match return_types.len() {
 => return Err(ParseError::new_error_str_at_pos(&module.source, open_curly_pos, "expected a return type")),
 => {},
             _ => return Err(ParseError::new_error_str_at_pos(&module.source, open_curly_pos, "multiple return types are not (yet) allowed")),
+        }
         // Consume block
         let body = self.consume_block_statement_without_leading_curly(module, iter, ctx, open_curly_pos)?;
         // Assign everything in the preallocated AST node
         let function = ctx.heap[definition_id].as_function_mut();
         function.return_types = return_types;
         function.parameters = parameters;
         function.body = body;
         Ok(())
+    }
     fn visit_component_definition(
         &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
     ) -> Result<(), ParseError> {
         // Consume component variant and name
         let (_variant_text, _) = consume_any_ident(&module.source, iter)?;
         debug_assert!(_variant_text == KW_PRIMITIVE || _variant_text == KW_COMPOSITE);
         let (ident_text, _) = consume_ident(&module.source, iter)?;
         // Retrieve preallocated definition
         let module_scope = SymbolScope::Module(module.root_id);
         let definition_id = ctx.symbols.get_symbol_by_name_defined_in_scope(module_scope, ident_text)
             .unwrap().variant.as_definition().definition_id;
         self.cur_definition = definition_id;
         consume_polymorphic_vars_spilled(&module.source, iter, ctx)?;
         // Parse component's argument list
         let mut parameter_section = self.variables.start_section();
         consume_parameter_list(
             &module.source, iter, ctx, &mut parameter_section, module_scope, definition_id
         )?;
         let parameters = parameter_section.into_vec();
         // Consume block
         let body = self.consume_block_statement(module, iter, ctx)?;
         // Assign everything in the AST node
         let component = ctx.heap[definition_id].as_component_mut();
         component.parameters = parameters;
         component.body = body;
         Ok(())
+    }
     /// Consumes a block statement. If the resulting statement is not a block
     /// (e.g. for a shorthand "if (expr) single_statement") then it will be
     /// wrapped in one
     fn consume_block_or_wrapped_statement(
         &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
     ) -> Result<BlockStatementId, ParseError> {
         if Some(TokenKind::OpenCurly) == iter.next() {
             // This is a block statement
             self.consume_block_statement(module, iter, ctx)
         } else {
             // Not a block statement, so wrap it in one
             let mut statements = self.statements.start_section();
             let wrap_begin_pos = iter.last_valid_pos();
             self.consume_statement(module, iter, ctx, &mut statements)?;
             let wrap_end_pos = iter.last_valid_pos();
             debug_assert_eq!(statements.len(), 1);
             let statements = statements.into_vec();
             let id = ctx.heap.alloc_block_statement(|this| BlockStatement{
                 this,
                 is_implicit: true,
                 span: InputSpan::from_positions(wrap_begin_pos, wrap_end_pos), // TODO: @Span
                 statements,
                 end_block: EndBlockStatementId::new_invalid(),
                 parent_scope: Scope::Definition(DefinitionId::new_invalid()),
                 first_unique_id_in_scope: -1,
                 next_unique_id_in_scope: -1,
                 relative_pos_in_parent: 0,
                 locals: Vec::new(),
                 labels: Vec::new()
             });
             let end_block = ctx.heap.alloc_end_block_statement(|this| EndBlockStatement{
                 this, start_block: id, next: StatementId::new_invalid()
             });
             let block_stmt = &mut ctx.heap[id];
             block_stmt.end_block = end_block;
             Ok(id)
+        }
+    }
     /// Consumes a statement and returns a boolean indicating whether it was a
     /// block or not.
     fn consume_statement(
         &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx, section: &mut ScopedSection<StatementId>
     ) -> Result<(), ParseError> {
         let next = iter.next().expect("consume_statement has a next token");
         if next == TokenKind::OpenCurly {
             let id = self.consume_block_statement(module, iter, ctx)?;
             section.push(id.upcast());
         } else if next == TokenKind::Ident {
             let ident = peek_ident(&module.source, iter).unwrap();
             if ident == KW_STMT_IF {
                 // Consume if statement and place end-if statement directly
                 // after it.
                 let id = self.consume_if_statement(module, iter, ctx)?;
                 section.push(id.upcast());
                 let end_if = ctx.heap.alloc_end_if_statement(|this| EndIfStatement{
                     this, start_if: id, next: StatementId::new_invalid()
                 });
                 section.push(end_if.upcast());
@@ @@ -742,887 +744,909 @@ impl PassDefinitions { @@
             span: channel_span,
             from, to,
             relative_pos_in_block: 0,
             next: StatementId::new_invalid(),
         }))
+    }
     fn consume_labeled_statement(
         &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx, section: &mut ScopedSection<StatementId>
     ) -> Result<(), ParseError> {
         let label = consume_ident_interned(&module.source, iter, ctx)?;
         consume_token(&module.source, iter, TokenKind::Colon)?;
         // Not pretty: consume_statement may produce more than one statement.
         // The values in the section need to be in the correct order if some
         // kind of outer block is consumed, so we take another section, push
         // the expressions in that one, and then allocate the labeled statement.
         let mut inner_section = self.statements.start_section();
         self.consume_statement(module, iter, ctx, &mut inner_section)?;
         debug_assert!(inner_section.len() >= 1);
         let stmt_id = ctx.heap.alloc_labeled_statement(|this| LabeledStatement {
             this,
             label,
             body: inner_section[0],
             relative_pos_in_block: 0,
             in_sync: None,
         });
         if inner_section.len() == 1 {
             // Produce the labeled statement pointing to the first statement.
             // This is by far the most common case.
             inner_section.forget();
             section.push(stmt_id.upcast());
         } else {
             // Produce the labeled statement using the first statement, and push
             // the remaining ones at the end.
             let inner_statements = inner_section.into_vec();
             section.push(stmt_id.upcast());
             for idx in 1..inner_statements.len() {
                 section.push(inner_statements[idx])
+            }
+        }
         Ok(())
+    }
     fn maybe_consume_memory_statement(
         &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
     ) -> Result<Option<(MemoryStatementId, ExpressionStatementId)>, ParseError> {
         // This is a bit ugly. It would be nicer if we could somehow
         // consume the expression with a type hint if we do get a valid
         // type, but we don't get an identifier following it
         let iter_state = iter.save();
         let definition_id = self.cur_definition;
         let poly_vars = ctx.heap[definition_id].poly_vars();
         let parser_type = consume_parser_type(
             &module.source, iter, &ctx.symbols, &ctx.heap, poly_vars,
             SymbolScope::Definition(definition_id), definition_id, true, 0
         );
         if let Ok(parser_type) = parser_type {
             if Some(TokenKind::Ident) == iter.next() {
                 // Assume this is a proper memory statement
                 let identifier = consume_ident_interned(&module.source, iter, ctx)?;
                 let memory_span = InputSpan::from_positions(parser_type.elements[0].full_span.begin, identifier.span.end);
                 let assign_span = consume_token(&module.source, iter, TokenKind::Equal)?;
                 let initial_expr_begin_pos = iter.last_valid_pos();
                 let initial_expr_id = self.consume_expression(module, iter, ctx)?;
                 let initial_expr_end_pos = iter.last_valid_pos();
                 consume_token(&module.source, iter, TokenKind::SemiColon)?;
                 // Allocate the memory statement with the variable
                 let local_id = ctx.heap.alloc_variable(|this| Variable{
                     this,
                     kind: VariableKind::Local,
                     identifier: identifier.clone(),
                     parser_type,
                     relative_pos_in_block: 0,
                     unique_id_in_scope: -1,
                 });
                 let memory_stmt_id = ctx.heap.alloc_memory_statement(|this| MemoryStatement{
                     this,
                     span: memory_span,
                     variable: local_id,
                     next: StatementId::new_invalid()
                 });
                 // Allocate the initial assignment
                 let variable_expr_id = ctx.heap.alloc_variable_expression(|this| VariableExpression{
                     this,
                     identifier,
                     declaration: None,
                     parent: ExpressionParent::None,
                     unique_id_in_definition: -1,
                     concrete_type: Default::default()
                 });
                 let assignment_expr_id = ctx.heap.alloc_assignment_expression(|this| AssignmentExpression{
                     this,
                     span: assign_span,
                     left: variable_expr_id.upcast(),
                     operation: AssignmentOperator::Set,
                     right: initial_expr_id,
                     parent: ExpressionParent::None,
                     unique_id_in_definition: -1,
                     concrete_type: Default::default(),
                 });
                 let assignment_stmt_id = ctx.heap.alloc_expression_statement(|this| ExpressionStatement{
                     this,
                     span: InputSpan::from_positions(initial_expr_begin_pos, initial_expr_end_pos),
                     expression: assignment_expr_id.upcast(),
                     next: StatementId::new_invalid(),
                 });
                 return Ok(Some((memory_stmt_id, assignment_stmt_id)))
+            }
+        }
         // If here then one of the preconditions for a memory statement was not
         // met. So recover the iterator and return
         iter.load(iter_state);
         Ok(None)
+    }
     fn consume_expression_statement(
         &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
     ) -> Result<ExpressionStatementId, ParseError> {
         let start_pos = iter.last_valid_pos();
         let expression = self.consume_expression(module, iter, ctx)?;
         let end_pos = iter.last_valid_pos();
         consume_token(&module.source, iter, TokenKind::SemiColon)?;
         Ok(ctx.heap.alloc_expression_statement(|this| ExpressionStatement{
             this,
             span: InputSpan::from_positions(start_pos, end_pos),
             expression,
             next: StatementId::new_invalid(),
         }))
+    }
     //--------------------------------------------------------------------------
     // Expression Parsing
     //--------------------------------------------------------------------------
     // TODO: @Cleanup This is fine for now. But I prefer my stacktraces not to
     //  look like enterprise Java code...
     fn consume_expression(
         &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
     ) -> Result<ExpressionId, ParseError> {
         self.consume_assignment_expression(module, iter, ctx)
+    }
     fn consume_assignment_expression(
         &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
     ) -> Result<ExpressionId, ParseError> {
         // Utility to convert token into assignment operator
         fn parse_assignment_operator(token: Option<TokenKind>) -> Option<AssignmentOperator> {
             use TokenKind as TK;
             use AssignmentOperator as AO;
             if token.is_none() {
                 return None
+            }
             match token.unwrap() {
                 TK::Equal               => Some(AO::Set),
                 TK::StarEquals          => Some(AO::Multiplied),
                 TK::SlashEquals         => Some(AO::Divided),
                 TK::PercentEquals       => Some(AO::Remained),
                 TK::PlusEquals          => Some(AO::Added),
                 TK::MinusEquals         => Some(AO::Subtracted),
                 TK::ShiftLeftEquals     => Some(AO::ShiftedLeft),
                 TK::ShiftRightEquals    => Some(AO::ShiftedRight),
                 TK::AndEquals           => Some(AO::BitwiseAnded),
                 TK::CaretEquals         => Some(AO::BitwiseXored),
                 TK::OrEquals            => Some(AO::BitwiseOred),
                 _                       => None
+            }
+        }
         let expr = self.consume_conditional_expression(module, iter, ctx)?;
         if let Some(operation) = parse_assignment_operator(iter.next()) {
             let span = iter.next_span();
             iter.consume();
             let left = expr;
             let right = self.consume_expression(module, iter, ctx)?;
             Ok(ctx.heap.alloc_assignment_expression(|this| AssignmentExpression{
                 this, span, left, operation, right,
                 parent: ExpressionParent::None,
                 unique_id_in_definition: -1,
                 concrete_type: ConcreteType::default(),
             }).upcast())
         } else {
             Ok(expr)
+        }
+    }
     fn consume_conditional_expression(
         &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
     ) -> Result<ExpressionId, ParseError> {
         let result = self.consume_concat_expression(module, iter, ctx)?;
         if let Some(TokenKind::Question) = iter.next() {
             let span = iter.next_span();
             iter.consume();
             let test = result;
             let true_expression = self.consume_expression(module, iter, ctx)?;
             consume_token(&module.source, iter, TokenKind::Colon)?;
             let false_expression = self.consume_expression(module, iter, ctx)?;
             Ok(ctx.heap.alloc_conditional_expression(|this| ConditionalExpression{
                 this, span, test, true_expression, false_expression,
                 parent: ExpressionParent::None,
                 unique_id_in_definition: -1,
                 concrete_type: ConcreteType::default(),
             }).upcast())
         } else {
             Ok(result)
+        }
+    }
     fn consume_concat_expression(
         &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
     ) -> Result<ExpressionId, ParseError> {
         self.consume_generic_binary_expression(
             module, iter, ctx,
             |token| match token {
                 Some(TokenKind::At) => Some(BinaryOperator::Concatenate),
                 _ => None
             },
             Self::consume_logical_or_expression
+        )
+    }
     fn consume_logical_or_expression(
         &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
     ) -> Result<ExpressionId, ParseError> {
         self.consume_generic_binary_expression(
             module, iter, ctx,
             |token| match token {
                 Some(TokenKind::OrOr) => Some(BinaryOperator::LogicalOr),
                 _ => None
             },
             Self::consume_logical_and_expression
+        )
+    }
     fn consume_logical_and_expression(
         &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
     ) -> Result<ExpressionId, ParseError> {
         self.consume_generic_binary_expression(
             module, iter, ctx,
             |token| match token {
                 Some(TokenKind::AndAnd) => Some(BinaryOperator::LogicalAnd),
                 _ => None
             },
             Self::consume_bitwise_or_expression
+        )
+    }
     fn consume_bitwise_or_expression(
         &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
     ) -> Result<ExpressionId, ParseError> {
         self.consume_generic_binary_expression(
             module, iter, ctx,
             |token| match token {
                 Some(TokenKind::Or) => Some(BinaryOperator::BitwiseOr),
                 _ => None
             },
             Self::consume_bitwise_xor_expression
+        )
+    }
     fn consume_bitwise_xor_expression(
         &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
     ) -> Result<ExpressionId, ParseError> {
         self.consume_generic_binary_expression(
             module, iter, ctx,
             |token| match token {
                 Some(TokenKind::Caret) => Some(BinaryOperator::BitwiseXor),
                 _ => None
             },
             Self::consume_bitwise_and_expression
+        )
+    }
     fn consume_bitwise_and_expression(
         &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
     ) -> Result<ExpressionId, ParseError> {
         self.consume_generic_binary_expression(
             module, iter, ctx,
             |token| match token {
                 Some(TokenKind::And) => Some(BinaryOperator::BitwiseAnd),
                 _ => None
             },
             Self::consume_equality_expression
+        )
+    }
     fn consume_equality_expression(
         &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
     ) -> Result<ExpressionId, ParseError> {
         self.consume_generic_binary_expression(
             module, iter, ctx,
             |token| match token {
                 Some(TokenKind::EqualEqual) => Some(BinaryOperator::Equality),
                 Some(TokenKind::NotEqual) => Some(BinaryOperator::Inequality),
                 _ => None
             },
             Self::consume_relational_expression
+        )
+    }
     fn consume_relational_expression(
         &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
     ) -> Result<ExpressionId, ParseError> {
         self.consume_generic_binary_expression(
             module, iter, ctx,
             |token| match token {
                 Some(TokenKind::OpenAngle) => Some(BinaryOperator::LessThan),
                 Some(TokenKind::CloseAngle) => Some(BinaryOperator::GreaterThan),
                 Some(TokenKind::LessEquals) => Some(BinaryOperator::LessThanEqual),
                 Some(TokenKind::GreaterEquals) => Some(BinaryOperator::GreaterThanEqual),
                 _ => None
             },
             Self::consume_shift_expression
+        )
+    }
     fn consume_shift_expression(
         &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
     ) -> Result<ExpressionId, ParseError> {
         self.consume_generic_binary_expression(
             module, iter, ctx,
             |token| match token {
                 Some(TokenKind::ShiftLeft) => Some(BinaryOperator::ShiftLeft),
                 Some(TokenKind::ShiftRight) => Some(BinaryOperator::ShiftRight),
                 _ => None
             },
             Self::consume_add_or_subtract_expression
+        )
+    }
     fn consume_add_or_subtract_expression(
         &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
     ) -> Result<ExpressionId, ParseError> {
         self.consume_generic_binary_expression(
             module, iter, ctx,
             |token| match token {
                 Some(TokenKind::Plus) => Some(BinaryOperator::Add),
                 Some(TokenKind::Minus) => Some(BinaryOperator::Subtract),
                 _ => None,
             },
             Self::consume_multiply_divide_or_modulus_expression
+        )
+    }
     fn consume_multiply_divide_or_modulus_expression(
         &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
     ) -> Result<ExpressionId, ParseError> {
         self.consume_generic_binary_expression(
             module, iter, ctx,
             |token| match token {
                 Some(TokenKind::Star) => Some(BinaryOperator::Multiply),
                 Some(TokenKind::Slash) => Some(BinaryOperator::Divide),
                 Some(TokenKind::Percent) => Some(BinaryOperator::Remainder),
                 _ => None
             },
             Self::consume_prefix_expression
+        )
+    }
     fn consume_prefix_expression(
         &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
     ) -> Result<ExpressionId, ParseError> {
         fn parse_prefix_token(token: Option<TokenKind>) -> Option<UnaryOperator> {
             use TokenKind as TK;
             use UnaryOperator as UO;
             match token {
                 Some(TK::Plus) => Some(UO::Positive),
                 Some(TK::Minus) => Some(UO::Negative),
                 Some(TK::PlusPlus) => Some(UO::PreIncrement),
                 Some(TK::MinusMinus) => Some(UO::PreDecrement),
                 Some(TK::Tilde) => Some(UO::BitwiseNot),
                 Some(TK::Exclamation) => Some(UO::LogicalNot),
                 _ => None
+            }
+        }
         if let Some(operation) = parse_prefix_token(iter.next()) {
             let span = iter.next_span();
             iter.consume();
             let expression = self.consume_prefix_expression(module, iter, ctx)?;
             Ok(ctx.heap.alloc_unary_expression(|this| UnaryExpression {
                 this, span, operation, expression,
                 parent: ExpressionParent::None,
                 unique_id_in_definition: -1,
                 concrete_type: ConcreteType::default()
             }).upcast())
         } else {
             self.consume_postfix_expression(module, iter, ctx)
+        }
+    }
     fn consume_postfix_expression(
         &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
     ) -> Result<ExpressionId, ParseError> {
         fn has_matching_postfix_token(token: Option<TokenKind>) -> bool {
             use TokenKind as TK;
             if token.is_none() { return false; }
             match token.unwrap() {
                 TK::PlusPlus | TK::MinusMinus | TK::OpenSquare | TK::Dot => true,
                 _ => false
+            }
+        }
         let mut result = self.consume_primary_expression(module, iter, ctx)?;
         let mut next = iter.next();
         while has_matching_postfix_token(next) {
             let token = next.unwrap();
             let mut span = iter.next_span();
             iter.consume();
             if token == TokenKind::PlusPlus {
                 result = ctx.heap.alloc_unary_expression(|this| UnaryExpression{
                     this, span,
                     operation: UnaryOperator::PostIncrement,
                     expression: result,
                     parent: ExpressionParent::None,
                     unique_id_in_definition: -1,
                     concrete_type: ConcreteType::default()
                 }).upcast();
             } else if token == TokenKind::MinusMinus {
                 result = ctx.heap.alloc_unary_expression(|this| UnaryExpression{
                     this, span,
                     operation: UnaryOperator::PostDecrement,
                     expression: result,
                     parent: ExpressionParent::None,
                     unique_id_in_definition: -1,
                     concrete_type: ConcreteType::default()
                 }).upcast();
             } else if token == TokenKind::OpenSquare {
                 let subject = result;
                 let from_index = self.consume_expression(module, iter, ctx)?;
                 // Check if we have an indexing or slicing operation
                 next = iter.next();
                 if Some(TokenKind::DotDot) == next {
                     iter.consume();
                     let to_index = self.consume_expression(module, iter, ctx)?;
                     let end_span = consume_token(&module.source, iter, TokenKind::CloseSquare)?;
                     span.end = end_span.end;
                     result = ctx.heap.alloc_slicing_expression(|this| SlicingExpression{
                         this, span, subject, from_index, to_index,
                         parent: ExpressionParent::None,
                         unique_id_in_definition: -1,
                         concrete_type: ConcreteType::default()
                     }).upcast();
                 } else if Some(TokenKind::CloseSquare) == next {
                     let end_span = consume_token(&module.source, iter, TokenKind::CloseSquare)?;
                     span.end = end_span.end;
                     result = ctx.heap.alloc_indexing_expression(|this| IndexingExpression{
                         this, span, subject,
                         index: from_index,
                         parent: ExpressionParent::None,
                         unique_id_in_definition: -1,
                         concrete_type: ConcreteType::default()
                     }).upcast();
                 } else {
                     return Err(ParseError::new_error_str_at_pos(
                         &module.source, iter.last_valid_pos(), "unexpected token: expected ']' or '..'"
                     ));
+                }
             } else {
                 debug_assert_eq!(token, TokenKind::Dot);
                 let subject = result;
                 let (field_text, field_span) = consume_ident(&module.source, iter)?;
                 let field = if field_text == b"length" {
                     Field::Length
                 } else {
                     let value = ctx.pool.intern(field_text);
                     let identifier = Identifier{ value, span: field_span };
                     Field::Symbolic(FieldSymbolic{ identifier, definition: None, field_idx: 0 })
                 };
                 result = ctx.heap.alloc_select_expression(|this| SelectExpression{
                     this, span, subject, field,
                     parent: ExpressionParent::None,
                     unique_id_in_definition: -1,
                     concrete_type: ConcreteType::default()
                 }).upcast();
+            }
             next = iter.next();
+        }
         Ok(result)
+    }
     fn consume_primary_expression(
         &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx
     ) -> Result<ExpressionId, ParseError> {
         let next = iter.next();
         let result = if next == Some(TokenKind::OpenParen) {
             // Expression between parentheses
             iter.consume();
             let result = self.consume_expression(module, iter, ctx)?;
             consume_token(&module.source, iter, TokenKind::CloseParen)?;
             result
         } else if next == Some(TokenKind::OpenCurly) {
             // Array literal
             let (start_pos, mut end_pos) = iter.next_positions();
             let mut scoped_section = self.expressions.start_section();
             consume_comma_separated(
                 TokenKind::OpenCurly, TokenKind::CloseCurly, &module.source, iter, ctx,
                 |_source, iter, ctx| self.consume_expression(module, iter, ctx),
                 &mut scoped_section, "an expression", "a list of expressions", Some(&mut end_pos)
             )?;
             ctx.heap.alloc_literal_expression(|this| LiteralExpression{
                 this,
                 span: InputSpan::from_positions(start_pos, end_pos),
                 value: Literal::Array(scoped_section.into_vec()),
                 parent: ExpressionParent::None,
                 unique_id_in_definition: -1,
                 concrete_type: ConcreteType::default(),
             }).upcast()
         } else if next == Some(TokenKind::Integer) {
             let (literal, span) = consume_integer_literal(&module.source, iter, &mut self.buffer)?;
             ctx.heap.alloc_literal_expression(|this| LiteralExpression{
                 this, span,
                 value: Literal::Integer(LiteralInteger{ unsigned_value: literal, negated: false }),
                 parent: ExpressionParent::None,
                 unique_id_in_definition: -1,
                 concrete_type: ConcreteType::default(),
             }).upcast()
         } else if next == Some(TokenKind::String) {
             let span = consume_string_literal(&module.source, iter, &mut self.buffer)?;
             let interned = ctx.pool.intern(self.buffer.as_bytes());
             ctx.heap.alloc_literal_expression(|this| LiteralExpression{
                 this, span,
                 value: Literal::String(interned),
                 parent: ExpressionParent::None,
                 unique_id_in_definition: -1,
                 concrete_type: ConcreteType::default(),
             }).upcast()
         } else if next == Some(TokenKind::Character) {
             let (character, span) = consume_character_literal(&module.source, iter)?;
             ctx.heap.alloc_literal_expression(|this| LiteralExpression{
                 this, span,
                 value: Literal::Character(character),
                 parent: ExpressionParent::None,
                 unique_id_in_definition: -1,
                 concrete_type: ConcreteType::default(),
             }).upcast()
         } else if next == Some(TokenKind::Ident) {
             // May be a variable, a type instantiation or a function call. If we
             // have a single identifier that we cannot find in the type table
             // then we're going to assume that we're dealing with a variable.
             let ident_span = iter.next_span();
             let ident_text = module.source.section_at_span(ident_span);
             let symbol = ctx.symbols.get_symbol_by_name(SymbolScope::Module(module.root_id), ident_text);
             if symbol.is_some() {
                 // The first bit looked like a symbol, so we're going to follow
                 // that all the way through, assume we arrive at some kind of
                 // function call or type instantiation
                 use ParserTypeVariant as PTV;
                 let symbol_scope = SymbolScope::Definition(self.cur_definition);
                 let poly_vars = ctx.heap[self.cur_definition].poly_vars();
                 let parser_type = consume_parser_type(
                     &module.source, iter, &ctx.symbols, &ctx.heap, poly_vars, symbol_scope,
                     self.cur_definition, true, 0
                 )?;
                 debug_assert!(!parser_type.elements.is_empty());
                 match parser_type.elements[0].variant {
                     PTV::Definition(target_definition_id, _) => {
                         let definition = &ctx.heap[target_definition_id];
                         match definition {
                             Definition::Struct(_) => {
                                 // Struct literal
                                 let mut last_token = iter.last_valid_pos();
                                 let mut struct_fields = Vec::new();
                                 consume_comma_separated(
                                     TokenKind::OpenCurly, TokenKind::CloseCurly, &module.source, iter, ctx,
                                     |source, iter, ctx| {
                                         let identifier = consume_ident_interned(source, iter, ctx)?;
                                         consume_token(source, iter, TokenKind::Colon)?;
                                         let value = self.consume_expression(module, iter, ctx)?;
                                         Ok(LiteralStructField{ identifier, value, field_idx: 0 })
                                     },
                                     &mut struct_fields, "a struct field", "a list of struct fields", Some(&mut last_token)
                                 )?;
                                 ctx.heap.alloc_literal_expression(|this| LiteralExpression{
                                     this,
                                     span: InputSpan::from_positions(ident_span.begin, last_token),
                                     value: Literal::Struct(LiteralStruct{
                                         parser_type,
                                         fields: struct_fields,
                                         definition: target_definition_id,
                                     }),
                                     parent: ExpressionParent::None,
                                     unique_id_in_definition: -1,
                                     concrete_type: ConcreteType::default(),
                                 }).upcast()
                             },
                             Definition::Enum(_) => {
                                 // Enum literal: consume the variant
                                 consume_token(&module.source, iter, TokenKind::ColonColon)?;
                                 let variant = consume_ident_interned(&module.source, iter, ctx)?;
                                 ctx.heap.alloc_literal_expression(|this| LiteralExpression{
                                     this,
                                     span: InputSpan::from_positions(ident_span.begin, variant.span.end),
                                     value: Literal::Enum(LiteralEnum{
                                         parser_type,
                                         variant,
                                         definition: target_definition_id,
                                         variant_idx: 0
                                     }),
                                     parent: ExpressionParent::None,
                                     unique_id_in_definition: -1,
                                     concrete_type: ConcreteType::default()
                                 }).upcast()
                             },
                             Definition::Union(_) => {
                                 // Union literal: consume the variant
                                 consume_token(&module.source, iter, TokenKind::ColonColon)?;
                                 let variant = consume_ident_interned(&module.source, iter, ctx)?;
                                 // Consume any possible embedded values
                                 let mut end_pos = variant.span.end;
                                 let values = if Some(TokenKind::OpenParen) == iter.next() {
                                     self.consume_expression_list(module, iter, ctx, Some(&mut end_pos))?
                                 } else {
                                     Vec::new()
                                 };
                                 ctx.heap.alloc_literal_expression(|this| LiteralExpression{
                                     this,
                                     span: InputSpan::from_positions(ident_span.begin, end_pos),
                                     value: Literal::Union(LiteralUnion{
                                         parser_type, variant, values,
                                         definition: target_definition_id,
                                         variant_idx: 0,
                                     }),
                                     parent: ExpressionParent::None,
                                     unique_id_in_definition: -1,
                                     concrete_type: ConcreteType::default()
                                 }).upcast()
                             },
                             Definition::Component(_) => {
                                 // Component instantiation
                                 let arguments = self.consume_expression_list(module, iter, ctx, None)?;
                                 ctx.heap.alloc_call_expression(|this| CallExpression{
                                     this,
                                     span: parser_type.elements[0].full_span, // TODO: @Span fix
                                     parser_type,
                                     method: Method::UserComponent,
                                     arguments,
                                     definition: target_definition_id,
                                     parent: ExpressionParent::None,
                                     unique_id_in_definition: -1,
                                     concrete_type: ConcreteType::default(),
                                 }).upcast()
                             },
                             Definition::Function(function_definition) => {
                                 // Check whether it is a builtin function
                                 let method = if function_definition.builtin {
                                     match function_definition.identifier.value.as_str() {
                                         "get" => Method::Get,
                                         "put" => Method::Put,
                                         "fires" => Method::Fires,
                                         "create" => Method::Create,
                                         "length" => Method::Length,
                                         "assert" => Method::Assert,
                                         _ => unreachable!(),
+                                    }
                                 } else {
                                     Method::UserFunction
                                 };
                                 // Function call: consume the arguments
                                 let arguments = self.consume_expression_list(module, iter, ctx, None)?;
                                 ctx.heap.alloc_call_expression(|this| CallExpression{
                                     this,
                                     span: parser_type.elements[0].full_span, // TODO: @Span fix
                                     parser_type,
                                     method,
                                     arguments,
                                     definition: target_definition_id,
                                     parent: ExpressionParent::None,
                                     unique_id_in_definition: -1,
                                     concrete_type: ConcreteType::default(),
                                 }).upcast()
+                            }
+                        }
                     },
                     _ => {
                         // TODO: Casting expressions
                         return Err(ParseError::new_error_str_at_span(
                             &module.source, parser_type.elements[0].full_span,
                             "unexpected type in expression, note that casting expressions are not yet implemented"
                         ))
+                    }
+                }
             } else {
                 // Check for builtin keywords or builtin functions
                 if ident_text == KW_LIT_NULL || ident_text == KW_LIT_TRUE || ident_text == KW_LIT_FALSE {
                     iter.consume();
                     // Parse builtin literal
                     let value = match ident_text {
                         KW_LIT_NULL => Literal::Null,
                         KW_LIT_TRUE => Literal::True,
                         KW_LIT_FALSE => Literal::False,
                         _ => unreachable!(),
                     };
                     ctx.heap.alloc_literal_expression(|this| LiteralExpression{
                         this,
                         span: ident_span,
                         value,
                         parent: ExpressionParent::None,
                         unique_id_in_definition: -1,
                         concrete_type: ConcreteType::default(),
                     }).upcast()
                 } else {
                     // Not a builtin literal, but also not a known type. So we
                     // assume it is a variable expression. Although if we do,
                     // then if a programmer mistyped a struct/function name the
                     // error messages will be rather cryptic. For polymorphic
                     // arguments we can't really do anything at all (because it
                     // uses the '<' token). In the other cases we try to provide
                     // a better error message.
                     iter.consume();
                     let next = iter.next();
                     if Some(TokenKind::ColonColon) == next {
                         return Err(ParseError::new_error_str_at_span(&module.source, ident_span, "unknown identifier"));
                     } else if Some(TokenKind::OpenParen) == next {
                         return Err(ParseError::new_error_str_at_span(
                             &module.source, ident_span,
                             "unknown identifier, did you mistype a union variant's or a function's name?"
                         ));
                     } else if Some(TokenKind::OpenCurly) == next {
                         return Err(ParseError::new_error_str_at_span(
                             &module.source, ident_span,
                             "unknown identifier, did you mistype a struct type's name?"
                         ))
+                    }
                     let ident_text = ctx.pool.intern(ident_text);
                     let identifier = Identifier { span: ident_span, value: ident_text };
                     ctx.heap.alloc_variable_expression(|this| VariableExpression {
                         this,
                         identifier,
                         declaration: None,
                         parent: ExpressionParent::None,
                         unique_id_in_definition: -1,
                         concrete_type: ConcreteType::default()
                     }).upcast()
+                }
+            }
         } else {
             return Err(ParseError::new_error_str_at_pos(
                 &module.source, iter.last_valid_pos(), "expected an expression"
             ));
         };
         Ok(result)
+    }
     //--------------------------------------------------------------------------
     // Expression Utilities
     //--------------------------------------------------------------------------
     #[inline]
     fn consume_generic_binary_expression<
         M: Fn(Option<TokenKind>) -> Option<BinaryOperator>,
         F: Fn(&mut PassDefinitions, &Module, &mut TokenIter, &mut PassCtx) -> Result<ExpressionId, ParseError>
     >(
         &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx, match_fn: M, higher_precedence_fn: F
     ) -> Result<ExpressionId, ParseError> {
         let mut result = higher_precedence_fn(self, module, iter, ctx)?;
         while let Some(operation) = match_fn(iter.next()) {
             let span = iter.next_span();
             iter.consume();
             let left = result;
             let right = higher_precedence_fn(self, module, iter, ctx)?;
             result = ctx.heap.alloc_binary_expression(|this| BinaryExpression{
                 this, span, left, operation, right,
                 parent: ExpressionParent::None,
                 unique_id_in_definition: -1,
                 concrete_type: ConcreteType::default()
             }).upcast();
+        }
         Ok(result)
+    }
     #[inline]
     fn consume_expression_list(
         &mut self, module: &Module, iter: &mut TokenIter, ctx: &mut PassCtx, end_pos: Option<&mut InputPosition>
     ) -> Result<Vec<ExpressionId>, ParseError> {
         let mut section = self.expressions.start_section();
         consume_comma_separated(
             TokenKind::OpenParen, TokenKind::CloseParen, &module.source, iter, ctx,
             |_source, iter, ctx| self.consume_expression(module, iter, ctx),
             &mut section, "an expression", "a list of expressions", end_pos
         )?;
         Ok(section.into_vec())
+    }
+}
 /// Consumes a type. A type always starts with an identifier which may indicate
 /// a builtin type or a user-defined type. The fact that it may contain
 /// polymorphic arguments makes it a tree-like structure. Because we cannot rely
 /// on knowing the exact number of polymorphic arguments we do not check for
 /// these.
 ///
 /// Note that the first depth index is used as a hack.
 // TODO: @Optimize, @Span fix, @Cleanup
 fn consume_parser_type(
     source: &InputSource, iter: &mut TokenIter, symbols: &SymbolTable, heap: &Heap, poly_vars: &[Identifier],
     cur_scope: SymbolScope, wrapping_definition: DefinitionId, allow_inference: bool, first_angle_depth: i32,
 ) -> Result<ParserType, ParseError> {
     struct Entry{
         element: ParserTypeElement,
         depth: i32,
+    }
     // After parsing the array modified "[]", we need to insert an array type
     // before the most recently parsed type.
     fn insert_array_before(elements: &mut Vec<Entry>, depth: i32, span: InputSpan) {
         let index = elements.iter().rposition(|e| e.depth == depth).unwrap();
         elements.insert(index, Entry{
             element: ParserTypeElement{ full_span: span, variant: ParserTypeVariant::Array },
             depth,
         });
+    }
     // Most common case we just have one type, perhaps with some array
     // annotations. This is both the hot-path, and simplifies the state machine
     // that follows and is responsible for parsing more complicated types.
     let element = consume_parser_type_ident(source, iter, symbols, heap, poly_vars, cur_scope, wrapping_definition, allow_inference)?;
     if iter.next() != Some(TokenKind::OpenAngle) {
         let num_embedded = element.variant.num_embedded();
         let mut num_array = 0;
         while iter.next() == Some(TokenKind::OpenSquare) {
             iter.consume();
             consume_token(source, iter, TokenKind::CloseSquare)?;
             num_array += 1;
+        }
         let array_span = element.full_span;
         let mut elements = Vec::with_capacity(num_array + num_embedded + 1);
         for _ in 0..num_array {
             elements.push(ParserTypeElement{ full_span: array_span, variant: ParserTypeVariant::Array });
+        }
         elements.push(element);
         if num_embedded != 0 {
             if !allow_inference {
                 return Err(ParseError::new_error_str_at_span(source, array_span, "type inference is not allowed here"));
+            }
             for _ in 0..num_embedded {
                 elements.push(ParserTypeElement { full_span: array_span, variant: ParserTypeVariant::Inferred });
+            }
+        }
         return Ok(ParserType{ elements });
     };
     // We have a polymorphic specification. So we start by pushing the item onto
     // our stack, then start adding entries together with the angle-brace depth
     // at which they're found.
     let mut elements = Vec::new();
     elements.push(Entry{ element, depth: 0 });
     // Start out with the first '<' consumed.
     iter.consume();
     enum State { Ident, Open, Close, Comma }
     let mut state = State::Open;
     let mut angle_depth = first_angle_depth + 1;
     loop {
         let next = iter.next();
@@ @@ -1764,206 +1788,206 @@ fn consume_parser_type( @@
                 let inserted_depth = cur_element.depth + 1;
                 elements.reserve(expected_subtypes);
                 for _ in 0..expected_subtypes {
                     elements.insert(idx + 1, Entry{
                         element: ParserTypeElement{ full_span: inserted_span, variant: ParserTypeVariant::Inferred },
                         depth: inserted_depth,
                     });
+                }
             } else {
                 // Mismatch in number of embedded types, produce a neat error
                 // message.
                 let type_name = String::from_utf8_lossy(source.section_at_span(cur_element.element.full_span));
                 fn polymorphic_name_text(num: usize) -> &'static str {
                     if num == 1 { "polymorphic argument" } else { "polymorphic arguments" }
+                }
                 fn were_or_was(num: usize) -> &'static str {
                     if num == 1 { "was" } else { "were" }
+                }
                 if expected_subtypes == 0 {
                     return Err(ParseError::new_error_at_span(
                         source, cur_element.element.full_span,
                         format!(
                             "the type '{}' is not polymorphic, yet {} {} {} provided",
                             type_name, encountered_subtypes, polymorphic_name_text(encountered_subtypes),
                             were_or_was(encountered_subtypes)
+                        )
                     ));
+                }
                 let maybe_infer_text = if allow_inference {
                     " (or none, to perform implicit type inference)"
                 } else {
                     ""
                 };
                 return Err(ParseError::new_error_at_span(
                     source, cur_element.element.full_span,
                     format!(
                         "expected {} {}{} for the type '{}', but {} {} provided",
                         expected_subtypes, polymorphic_name_text(expected_subtypes),
                         maybe_infer_text, type_name, encountered_subtypes,
                         were_or_was(encountered_subtypes)
+                    )
                 ));
+            }
+        }
         idx += 1;
+    }
     let mut constructed_elements = Vec::with_capacity(elements.len());
     for element in elements.into_iter() {
         constructed_elements.push(element.element);
+    }
     Ok(ParserType{ elements: constructed_elements })
+}
 /// Consumes an identifier for which we assume that it resolves to some kind of
 /// type. Once we actually arrive at a type we will stop parsing. Hence there
 /// may be trailing '::' tokens in the iterator.
 fn consume_parser_type_ident(
     source: &InputSource, iter: &mut TokenIter, symbols: &SymbolTable, heap: &Heap, poly_vars: &[Identifier],
     mut scope: SymbolScope, wrapping_definition: DefinitionId, allow_inference: bool,
 ) -> Result<ParserTypeElement, ParseError> {
     use ParserTypeVariant as PTV;
     let (mut type_text, mut type_span) = consume_any_ident(source, iter)?;
     let variant = match type_text {
         KW_TYPE_MESSAGE => PTV::Message,
         KW_TYPE_BOOL => PTV::Bool,
         KW_TYPE_UINT8 => PTV::UInt8,
         KW_TYPE_UINT16 => PTV::UInt16,
         KW_TYPE_UINT32 => PTV::UInt32,
         KW_TYPE_UINT64 => PTV::UInt64,
         KW_TYPE_SINT8 => PTV::SInt8,
         KW_TYPE_SINT16 => PTV::SInt16,
         KW_TYPE_SINT32 => PTV::SInt32,
         KW_TYPE_SINT64 => PTV::SInt64,
         KW_TYPE_IN_PORT => PTV::Input,
         KW_TYPE_OUT_PORT => PTV::Output,
         KW_TYPE_CHAR => PTV::Character,
         KW_TYPE_STRING => PTV::String,
         KW_TYPE_INFERRED => {
             if !allow_inference {
                 return Err(ParseError::new_error_str_at_span(source, type_span, "type inference is not allowed here"));
+            }
             PTV::Inferred
         },
         _ => {
             // Must be some kind of symbolic type
             let mut type_kind = None;
             for (poly_idx, poly_var) in poly_vars.iter().enumerate() {
                 if poly_var.value.as_bytes() == type_text {
                     type_kind = Some(PTV::PolymorphicArgument(wrapping_definition, poly_idx));
+                    type_kind = Some(PTV::PolymorphicArgument(wrapping_definition, poly_idx as u32));
+                }
+            }
             if type_kind.is_none() {
                 // Check symbol table for definition. To be fair, the language
                 // only allows a single namespace for now. That said:
                 let last_symbol = symbols.get_symbol_by_name(scope, type_text);
                 if last_symbol.is_none() {
                     return Err(ParseError::new_error_str_at_span(source, type_span, "unknown type"));
+                }
                 let mut last_symbol = last_symbol.unwrap();
                 loop {
                     match &last_symbol.variant {
                         SymbolVariant::Module(symbol_module) => {
                             // Expecting more identifiers
                             if Some(TokenKind::ColonColon) != iter.next() {
                                 return Err(ParseError::new_error_str_at_span(source, type_span, "expected a type but got a module"));
+                            }
                             consume_token(source, iter, TokenKind::ColonColon)?;
                             // Consume next part of type and prepare for next
                             // lookup loop
                             let (next_text, next_span) = consume_any_ident(source, iter)?;
                             let old_text = type_text;
                             type_text = next_text;
                             type_span.end = next_span.end;
                             scope = SymbolScope::Module(symbol_module.root_id);
                             let new_symbol = symbols.get_symbol_by_name_defined_in_scope(scope, type_text);
                             if new_symbol.is_none() {
                                 // If the type is imported in the module then notify the programmer
                                 // that imports do not leak outside of a module
                                 let type_name = String::from_utf8_lossy(type_text);
                                 let module_name = String::from_utf8_lossy(old_text);
                                 let suffix = if symbols.get_symbol_by_name(scope, type_text).is_some() {
                                     format!(
                                         ". The module '{}' does import '{}', but these imports are not visible to other modules",
                                         &module_name, &type_name
+                                    )
                                 } else {
                                     String::new()
                                 };
                                 return Err(ParseError::new_error_at_span(
                                     source, next_span,
                                     format!("unknown type '{}' in module '{}'{}", type_name, module_name, suffix)
                                 ));
+                            }
                             last_symbol = new_symbol.unwrap();
                         },
                         SymbolVariant::Definition(symbol_definition) => {
                             let num_poly_vars = heap[symbol_definition.definition_id].poly_vars().len();
                             type_kind = Some(PTV::Definition(symbol_definition.definition_id, num_poly_vars));
+                            type_kind = Some(PTV::Definition(symbol_definition.definition_id, num_poly_vars as u32));
                             break;
+                        }
+                    }
+                }
+            }
             debug_assert!(type_kind.is_some());
             type_kind.unwrap()
         },
     };
     Ok(ParserTypeElement{ full_span: type_span, variant })
+}
 /// Consumes polymorphic variables and throws them on the floor.
 fn consume_polymorphic_vars_spilled(source: &InputSource, iter: &mut TokenIter, _ctx: &mut PassCtx) -> Result<(), ParseError> {
     maybe_consume_comma_separated_spilled(
         TokenKind::OpenAngle, TokenKind::CloseAngle, source, iter, _ctx,
         |source, iter, _ctx| {
             consume_ident(source, iter)?;
             Ok(())
         }, "a polymorphic variable"
     )?;
     Ok(())
+}
 /// Consumes the parameter list to functions/components
 fn consume_parameter_list(
     source: &InputSource, iter: &mut TokenIter, ctx: &mut PassCtx,
     target: &mut ScopedSection<VariableId>, scope: SymbolScope, definition_id: DefinitionId
 ) -> Result<(), ParseError> {
     consume_comma_separated(
         TokenKind::OpenParen, TokenKind::CloseParen, source, iter, ctx,
         |source, iter, ctx| {
             let poly_vars = ctx.heap[definition_id].poly_vars(); // TODO: @Cleanup, this is really ugly. But rust...
             let parser_type = consume_parser_type(
                 source, iter, &ctx.symbols, &ctx.heap, poly_vars, scope,
                 definition_id, false, 0
             )?;
             let identifier = consume_ident_interned(source, iter, ctx)?;
             let parameter_id = ctx.heap.alloc_variable(|this| Variable{
                 this,
                 kind: VariableKind::Parameter,
                 parser_type,
                 identifier,
                 relative_pos_in_block: 0,
                 unique_id_in_scope: -1,
             });
             Ok(parameter_id)
         },
         target, "a parameter", "a parameter list", None
+    )
+}
@@ \ No newline at end of file @@

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 casee we return an
 /// error.
 ///
 /// Inference may be applied on non-polymorphic procedures and on polymorphic
 /// procedures. When dealing with a non-polymorphic procedure we apply the type
 /// resolver and annotate the AST with the `ConcreteType`s. When dealing with
 /// polymorphic procedures we will only annotate the AST once, preserving
 /// references to polymorphic variables. Any later pass will perform just the
 /// type checking.
 ///
 /// TODO: Needs a thorough rewrite:
 ///  0. polymorph_progress is intentionally broken at the moment.
 ///  1. For polymorphic type inference we need to have an extra datastructure
 ///     for progressing the polymorphic variables and mapping them back to each
 ///     signature type that uses that polymorphic type. The two types of markers
 ///     became somewhat of a mess.
 ///  2. We're doing a lot of extra work. It seems better to apply the initial
 ///     type based on expression parents, then to apply forced constraints (arg
 ///     to a fires() call must be port-like), only then to start progressing the
 ///     types.
 ///     Furthermore, queueing of expressions can be more intelligent, currently
 ///     every child/parent of an expression is inferred again when queued. Hence
 ///     we need to queue only specific children/parents of expressions.
 ///  3. Remove the `msg` type?
 ///  4. Disallow certain types in certain operations (e.g. `Void`).
 ///  5. Implement implicit and explicit casting.
 ///  6. Investigate different ways of performing the type-on-type inference,
 ///     maybe there is a better way then flattened trees + markers?
 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,
     Visitor2,
     VisitorResult
 };
 use std::collections::hash_map::Entry;
 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; 1] = [ InferenceTypePart::String ];
 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
 /// TODO: @types Remove the Message -> Byte hack at some point...
 #[derive(Debug, Clone, Eq, PartialEq)]
 pub(crate) enum InferenceTypePart {
     // A marker with an identifier which we can use to retrieve the type subtree
     // that follows the marker. This is used to perform type inference on
     // polymorphs: an expression may determine the polymorphs type, after we
     // need to apply that information to all other places where the polymorph is
     // used.
     MarkerDefinition(usize), // marker for polymorph types on a procedure's definition
     MarkerBody(usize), // marker for polymorph types within a procedure body
     // 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,
     // A user-defined type with any number of subtypes
-    Instance(DefinitionId, usize)
+    Instance(DefinitionId, u32)
+}
 impl InferenceTypePart {
     fn is_marker(&self) -> bool {
         use InferenceTypePart as ITP;
         match self {
-            ITP::MarkerDefinition(_) | ITP::MarkerBody(_) => true,
+            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,
         match self {
             ITP::UInt8 | ITP::UInt16 | ITP::UInt32 | ITP::UInt64 |
             ITP::SInt8 | ITP::SInt16 | ITP::SInt32 | ITP::SInt64 => true,
             _ => false,
+        }
+    }
     fn is_concrete_msg_array_or_slice(&self) -> bool {
         use InferenceTypePart as ITP;
         match self {
             ITP::Array | ITP::Slice | 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_msg_array_or_slice()) ||
         (*self == ITP::PortLike && arg.is_concrete_port())
+    }
     /// 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 | ITP::String => {
                 -1
             },
-            ITP::MarkerDefinition(_) | ITP::MarkerBody(_) |
+            ITP::Marker(_) |
             ITP::ArrayLike | ITP::Message | ITP::Array | ITP::Slice |
             ITP::PortLike | ITP::Input | ITP::Output => {
                 // One subtype, so do not modify depth
             },
             ITP::Instance(_, num_args) => {
                 (*num_args as i32) - 1
+            }
+        }
+    }
+}
 impl From<ConcreteTypePart> for InferenceTypePart {
     fn from(v: ConcreteTypePart) -> InferenceTypePart {
         use ConcreteTypePart as CTP;
         use InferenceTypePart as ITP;
         match v {
             CTP::Marker(_) => {
                 unreachable!("encountered marker while converting concrete type to inferred type");
+            }
             CTP::Void => ITP::Void,
             CTP::Message => ITP::Message,
             CTP::Bool => ITP::Bool,
             CTP::UInt8 => ITP::UInt8,
             CTP::UInt16 => ITP::UInt16,
             CTP::UInt32 => ITP::UInt32,
             CTP::UInt64 => ITP::UInt64,
             CTP::SInt8 => ITP::SInt8,
             CTP::SInt16 => ITP::SInt16,
             CTP::SInt32 => ITP::SInt32,
             CTP::SInt64 => ITP::SInt64,
             CTP::Character => ITP::Character,
             CTP::String => ITP::String,
             CTP::Array => ITP::Array,
             CTP::Slice => ITP::Slice,
             CTP::Input => ITP::Input,
             CTP::Output => ITP::Output,
             CTP::Instance(id, num) => ITP::Instance(id, num),
+        }
+    }
+}
 #[derive(Debug)]
 struct InferenceType {
-    has_body_marker: bool,
+    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_body_marker: bool, is_done: bool, parts: Vec<InferenceTypePart>) -> Self {
+    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| {
                 if let InferenceTypePart::MarkerBody(_) = v { true } else { false }
             });
             debug_assert_eq!(has_body_marker, parts_body_marker);
             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_body_marker, is_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_body_marker(&self, mut start_idx: usize) -> Option<(usize, usize)> {
+    fn find_marker(&self, mut start_idx: usize) -> Option<(usize, usize)> {
         while start_idx < self.parts.len() {
             if let InferenceTypePart::MarkerBody(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 body_marker_iter(&self) -> InferenceTypeMarkerIter {
+    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!();
+    }
     /// 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];
         // TODO: Maybe do this differently?
         let mut template_definition_marker = None;
         if *template_idx > 0 {
             if let ITP::MarkerDefinition(marker) = &template_parts[*template_idx - 1] {
                 template_definition_marker = Some(*marker)
+            }
+        }
         // 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());
             if let Some(marker) = template_definition_marker {
                 to_infer.parts.insert(*to_infer_idx, ITP::MarkerDefinition(marker));
                 *to_infer_idx += 1;
+            }
             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 to copy definition markers, but not to
             // transfer polymorph markers.
             // entire subtree. Make sure not to copy markers.
             let template_end_idx = Self::find_subtree_end_idx(template_parts, *template_idx);
             let template_start_idx = if let Some(marker) = template_definition_marker {
                 to_infer.parts[*to_infer_idx] = ITP::MarkerDefinition(marker);
                 *template_idx
             } else {
                 to_infer.parts[*to_infer_idx] = template_parts[*template_idx].clone();
                 *template_idx + 1
             };
             *to_infer_idx += 1;
-            for template_idx in template_start_idx..template_end_idx {
+            for template_idx in *template_idx..template_end_idx {
                 let template_part = &template_parts[template_idx];
                 if let ITP::MarkerBody(_) = template_part {
                     // Do not copy this one
                 } else {
                 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;
+            }
-            // And can also not be inferred in any way: types must be incompatible
+            // 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`.
     /// Secondary use is to make sure that a type follows a certain template.
     fn infer_subtree_for_single_type(
         to_infer: &mut InferenceType, mut to_infer_idx: usize,
         template: &[InferenceTypePart], mut template_idx: usize,
     ) -> 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;
+            }
             // 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
+        }
-        return if modified {
         if modified {
             to_infer.recompute_is_done();
             SingleInferenceResult::Modified
+            return SingleInferenceResult::Modified;
         } else {
             SingleInferenceResult::Unmodified
+            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.
-    fn write_concrete_type(&self, concrete_type: &mut ConcreteType, discard_marked_types: bool) {
     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());
         debug_assert!(concrete_type.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::MarkerDefinition(marker) => {
                     // When annotating the AST we keep the markers. When
                     // determining types for monomorphs we instead want to
                     // keep the type (not the markers)
                     if discard_marked_types {
                         idx = InferenceType::find_subtree_end_idx(&self.parts, idx + 1);
                         concrete_type.parts.push(CTP::Marker(*marker));
                     } else {
                         idx += 1;
+                    }
                     continue;
                 },
                 ITP::MarkerBody(_) => {
                     // Inner markers are removed when writing to the concrete
                     // type.
                 ITP::Marker(_) => {
                     // Markers are removed when writing to the concrete type.
                     idx += 1;
                     continue;
                 },
                 ITP::Unknown | ITP::NumberLike | ITP::IntegerLike | ITP::ArrayLike | ITP::PortLike => {
                     unreachable!("Attempted to convert inference type part {:?} into concrete type", part);
                     // 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 => CTP::String,
                 ITP::Array => CTP::Array,
                 ITP::Slice => CTP::Slice,
                 ITP::Input => CTP::Input,
                 ITP::Output => CTP::Output,
                 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::MarkerDefinition(thing) => {
                 buffer.push_str(&format!("{{D:{}}}", *thing));
                 idx = Self::write_display_name(buffer, heap, parts, idx + 1);
             },
             ITP::MarkerBody(thing) => {
                 buffer.push_str(&format!("{{B:{}}}", *thing));
             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),
             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::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 = (usize, &'a [InferenceTypePart]);
+    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::MarkerBody(marker) = self.parts[self.idx] {
+            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(),
+        }
+    }
+}
 #[derive(PartialEq, Eq)]
 pub(crate) struct ResolveQueueElement {
     pub(crate) root_id: RootId,
     pub(crate) definition_id: DefinitionId,
     pub(crate) monomorph_types: Vec<ConcreteType>,
+}
 pub(crate) type ResolveQueue = Vec<ResolveQueueElement>;
 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
     var_or_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,
             var_or_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.
     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: HashMap<ExpressionId, InferenceType>,   // types of expressions
     extra_data: HashMap<ExpressionId, ExtraData>,       // data for polymorph inference
     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: HashSet<ExpressionId>,
+    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 {
     /// 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{
             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 {
             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: HashMap::new(),
             extra_data: HashMap::new(),
             expr_queued: HashSet::new(),
             expr_types: Vec::new(),
             extra_data: Vec::new(),
             expr_queued: DequeSet::new(),
+        }
+    }
     // TODO: @cleanup Unsure about this, maybe a pattern will arise after
     //  a while.
     pub(crate) fn queue_module_definitions(ctx: &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];
             match definition {
                 Definition::Function(definition) => {
                     if definition.poly_vars.is_empty() {
                         queue.push(ResolveQueueElement{
                             root_id,
                             definition_id: *definition_id,
                             monomorph_types: Vec::new(),
                         })
+                    }
                 },
                 Definition::Component(definition) => {
                     if definition.poly_vars.is_empty() {
                         queue.push(ResolveQueueElement{
                             root_id,
                             definition_id: *definition_id,
                             monomorph_types: Vec::new(),
                         })
+                    }
                 },
                 Definition::Enum(_) | Definition::Struct(_) | Definition::Union(_) => {},
+            }
+        }
+    }
     pub(crate) fn handle_module_definition(
         &mut self, ctx: &mut Ctx, queue: &mut ResolveQueue, element: ResolveQueueElement
     ) -> VisitorResult {
         // Visit the definition
         debug_assert_eq!(ctx.module.root_id, element.root_id);
         self.reset();
         self.poly_vars.clear();
         self.poly_vars.extend(element.monomorph_types.iter().cloned());
         self.visit_definition(ctx, element.definition_id)?;
         // Keep resolving types
         self.resolve_types(ctx, queue)?;
         Ok(())
+    }
     fn reset(&mut self) {
         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 Visitor2 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();
                 for concrete_part in &poly_var.parts {
                     infer_type_parts.push(InferenceTypePart::from(*concrete_part));
+                }
                 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_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_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.expr_types.insert(test_expr_id, InferenceType::new(false, true, vec![InferenceTypePart::Bool]));
         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 {
         // TODO: @Monomorph, this is a temporary hack, see other comments
         let expr = &mut ctx.heap[id];
         if let Field::Symbolic(field) = &mut expr.field {
             field.definition = None;
             field.field_idx = 0;
+        }
         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_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);
         // TODO: @performance
         let call_expr = &ctx.heap[id];
         for arg_expr_id in call_expr.arguments.clone() {
             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());
         let var_data = self.var_types.get_mut(var_expr.declaration.as_ref().unwrap()).unwrap();
         var_data.used_at.push(upcast_id);
         self.progress_variable_expr(ctx, id)
+    }
+}
 macro_rules! debug_assert_expr_ids_unique_and_known {
     // Base case for a single expression ID
     ($resolver:ident, $id:ident) => {
         if cfg!(debug_assertions) {
             $resolver.expr_types.contains_key(&$id);
+        }
     };
     // Base case for two expression IDs
     ($resolver:ident, $id1:ident, $id2:ident) => {
         debug_assert_ne!($id1, $id2);
         debug_assert_expr_ids_unique_and_known!($resolver, $id1);
         debug_assert_expr_ids_unique_and_known!($resolver, $id2);
     };
     // Generic case
     ($resolver:ident, $id1:ident, $id2:ident, $($tail:ident),+) => {
         debug_assert_ne!($id1, $id2);
         debug_assert_expr_ids_unique_and_known!($resolver, $id1);
         debug_assert_expr_ids_unique_and_known!($resolver, $id2, $($tail),+);
     };
+}
 macro_rules! debug_assert_ptrs_distinct {
     // Base case
     ($ptr1:ident, $ptr2:ident) => {
         debug_assert!(!std::ptr::eq($ptr1, $ptr2));
     };
     // Generic case
     ($ptr1:ident, $ptr2:ident, $($tail:ident),+) => {
         debug_assert_ptrs_distinct!($ptr1, $ptr2);
         debug_assert_ptrs_distinct!($ptr2, $($tail),+);
     };
+}
 impl PassTyping {
     fn resolve_types(&mut self, ctx: &mut Ctx, queue: &mut ResolveQueue) -> Result<(), ParseError> {
         // Keep inferring until we can no longer make any progress
         while let Some(next_expr_id) = self.expr_queued.iter().next() {
             let next_expr_id = *next_expr_id;
             self.expr_queued.remove(&next_expr_id);
             self.progress_expr(ctx, next_expr_id)?;
+        }
         // We check if we have all the types we need. If we're typechecking a
         // polymorphic procedure more than once, then we have already annotated
         // the AST and have now performed typechecking for a different
         // monomorph. In that case we just need to perform typechecking, no need
         // to annotate the AST again.
         // TODO: @Monomorph, this is completely wrong. It seemed okay, but it
         //  isn't. Each monomorph might result in completely different internal
         //  types.
         let definition_id = match &self.definition_type {
             DefinitionType::Component(id) => id.upcast(),
             DefinitionType::Function(id) => id.upcast(),
         };
         let already_checked = ctx.types.get_base_definition(&definition_id).unwrap().has_any_monomorph();
         for (expr_id, expr_type) in self.expr_types.iter_mut() {
             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;
                 } else {
                     let expr = &ctx.heap[*expr_id];
                     return Err(ParseError::new_error_at_span(
                         &ctx.module.source, expr.span(), format!(
                             "could not fully infer the type of this expression (got '{}')",
                             expr_type.display_name(&ctx.heap)
+                        )
                     ));
+                }
+            }
             if !already_checked {
                 let concrete_type = ctx.heap[*expr_id].get_type_mut();
-                expr_type.write_concrete_type(concrete_type, true);
                 expr_type.write_concrete_type(concrete_type);
             } else {
                 if cfg!(debug_assertions) {
                     let mut concrete_type = ConcreteType::default();
-                    expr_type.write_concrete_type(&mut concrete_type, true);
                     expr_type.write_concrete_type(&mut concrete_type);
                     debug_assert_eq!(*ctx.heap[*expr_id].get_type(), concrete_type);
+                }
+            }
+        }
         // All types are fine
         ctx.types.add_monomorph(&definition_id, self.poly_vars.clone());
         // Check all things we need to monomorphize
         // TODO: Struct/enum/union monomorphization
         for (expr_id, extra_data) in self.extra_data.iter() {
             if extra_data.poly_vars.is_empty() { continue; }
             // Retrieve polymorph variable specification. Those of struct
             // literals and those of procedure calls need to be fully inferred.
             // The remaining ones (e.g. select expressions) allow partial
             // inference of types, as long as the accessed field's type is
             // fully inferred.
             let needs_full_inference = match &ctx.heap[*expr_id] {
                 Expression::Call(_) => true,
                 Expression::Literal(_) => true,
                 _ => false
             };
             if needs_full_inference {
                 let mut monomorph_types = Vec::with_capacity(extra_data.poly_vars.len());
                 for (poly_idx, poly_type) in extra_data.poly_vars.iter().enumerate() {
                     if !poly_type.is_done {
                         // TODO: Single clean function for function signatures and polyvars.
                         // TODO: Better error message
                         let expr = &ctx.heap[*expr_id];
                         return Err(ParseError::new_error_at_span(
                             &ctx.module.source, expr.span(), format!(
                                 "could not fully infer the type of polymorphic variable {} of this expression (got '{}')",
                                 poly_idx, poly_type.display_name(&ctx.heap)
+                            )
                         ))
+                    }
                     let mut concrete_type = ConcreteType::default();
-                    poly_type.write_concrete_type(&mut concrete_type, false);
                     poly_type.write_concrete_type(&mut concrete_type);
                     monomorph_types.insert(poly_idx, concrete_type);
+                }
                 // Resolve to the appropriate expression and instantiate
                 // monomorphs.
                 match &ctx.heap[*expr_id] {
                     Expression::Call(call_expr) => {
                         // Add to type table if not yet typechecked
                         if call_expr.method == Method::UserFunction {
                             let definition_id = call_expr.definition;
                             if !ctx.types.has_monomorph(&definition_id, &monomorph_types) {
                                 let root_id = ctx.types
                                     .get_base_definition(&definition_id)
                                     .unwrap()
                                     .ast_root;
                                 // Pre-emptively add the monomorph to the type table, but
                                 // we still need to perform typechecking on it
                                 // TODO: Unsure about this, performance wise
                                 let queue_element = ResolveQueueElement{
                                     root_id,
                                     definition_id,
                                     monomorph_types,
                                 };
                                 if !queue.contains(&queue_element) {
                                     queue.push(queue_element);
+                                }
+                            }
+                        }
                     },
                     Expression::Literal(lit_expr) => {
                         let definition_id = match &lit_expr.value {
                             Literal::Struct(literal) => &literal.definition,
                             Literal::Enum(literal) => &literal.definition,
                             Literal::Union(literal) => &literal.definition,
                             _ => unreachable!("post-inference monomorph for non-struct, non-enum, non-union literal")
                         };
                         if !ctx.types.has_monomorph(definition_id, &monomorph_types) {
                             ctx.types.add_monomorph(definition_id, monomorph_types);
+                        }
                     },
                     _ => unreachable!("needs fully inference, but not a struct literal or call expression")
+                }
             } // else: was just a helper structure...
+        }
         Ok(())
+    }
     fn progress_expr(&mut self, ctx: &mut Ctx, id: ExpressionId) -> Result<(), ParseError> {
         match &ctx.heap[id] {
             Expression::Assignment(expr) => {
                 let id = expr.this;
                 self.progress_assignment_expr(ctx, id)
             },
             Expression::Binding(_expr) => {
                 unimplemented!("progress binding expression");
             },
             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::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)
+            }
+        }
+    }
@@ @@ -1710,204 +1694,205 @@ impl PassTyping { @@
         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.expr_types.get(&arg_id).unwrap().display_name(&ctx.heap));
         debug_log!("   - Expr type: {}", self.expr_types.get(&upcast_id).unwrap().display_name(&ctx.heap));
         let (progress_expr, progress_arg) = match expr.operation {
             UO::Positive | UO::Negative => {
                 // Equal types of numeric class
                 let progress_base = self.apply_forced_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 | UO::PreIncrement | UO::PreDecrement | UO::PostIncrement | UO::PostDecrement => {
                 // Equal types of integer class
                 let progress_base = self.apply_forced_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 booleans
                 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.expr_types.get(&arg_id).unwrap().display_name(&ctx.heap));
         debug_log!("   - Expr type [{}]: {}", progress_expr, self.expr_types.get(&upcast_id).unwrap().display_name(&ctx.heap));
         if progress_expr { self.queue_expr_parent(ctx, upcast_id); }
         if progress_arg { self.queue_expr(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.expr_types.get(&subject_id).unwrap().display_name(&ctx.heap));
         debug_log!("   - Index   type: {}", self.expr_types.get(&index_id).unwrap().display_name(&ctx.heap));
         debug_log!("   - Expr    type: {}", self.expr_types.get(&upcast_id).unwrap().display_name(&ctx.heap));
         // Make sure subject is arraylike and index is integerlike
         let progress_subject_base = self.apply_forced_constraint(ctx, subject_id, &ARRAYLIKE_TEMPLATE)?;
         let progress_index = self.apply_forced_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.expr_types.get(&subject_id).unwrap().display_name(&ctx.heap));
         debug_log!("   - Index   type [{}]: {}", progress_index, self.expr_types.get(&index_id).unwrap().display_name(&ctx.heap));
         debug_log!("   - Expr    type [{}]: {}", progress_expr, self.expr_types.get(&upcast_id).unwrap().display_name(&ctx.heap));
         if progress_expr { self.queue_expr_parent(ctx, upcast_id); }
         if progress_subject_base || progress_subject { self.queue_expr(subject_id); }
         if progress_index { self.queue_expr(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.expr_types.get(&subject_id).unwrap().display_name(&ctx.heap));
         debug_log!("   - FromIdx type: {}", self.expr_types.get(&from_id).unwrap().display_name(&ctx.heap));
         debug_log!("   - ToIdx   type: {}", self.expr_types.get(&to_id).unwrap().display_name(&ctx.heap));
         debug_log!("   - Expr    type: {}", self.expr_types.get(&upcast_id).unwrap().display_name(&ctx.heap));
         // Make sure subject is arraylike and indices are of equal integerlike
         let progress_subject_base = self.apply_forced_constraint(ctx, subject_id, &ARRAYLIKE_TEMPLATE)?;
         let progress_idx_base = self.apply_forced_constraint(ctx, from_id, &INTEGERLIKE_TEMPLATE)?;
         let (progress_from, progress_to) = self.apply_equal2_constraint(ctx, upcast_id, from_id, 0, to_id, 0)?;
         // Make sure if output is of T then subject is Array<T>
         // Make sure if output is of Slice<T> then subject is Array<T>
         let progress_expr_base = self.apply_forced_constraint(ctx, upcast_id, &SLICE_TEMPLATE)?;
         let (progress_expr, progress_subject) =
-            self.apply_equal2_constraint(ctx, upcast_id, upcast_id, 0, subject_id, 0)?;
+            self.apply_equal2_constraint(ctx, upcast_id, upcast_id, 1, subject_id, 1)?;
         debug_log!(" * After:");
         debug_log!("   - Subject type [{}]: {}", progress_subject_base || progress_subject, self.expr_types.get(&subject_id).unwrap().display_name(&ctx.heap));
         debug_log!("   - FromIdx type [{}]: {}", progress_idx_base || progress_from, self.expr_types.get(&from_id).unwrap().display_name(&ctx.heap));
         debug_log!("   - ToIdx   type [{}]: {}", progress_idx_base || progress_to, self.expr_types.get(&to_id).unwrap().display_name(&ctx.heap));
         debug_log!("   - Expr    type [{}]: {}", progress_expr, self.expr_types.get(&upcast_id).unwrap().display_name(&ctx.heap));
         if progress_expr { self.queue_expr_parent(ctx, upcast_id); }
+        if progress_expr_base || progress_expr { self.queue_expr_parent(ctx, upcast_id); }
         if progress_subject_base || progress_subject { self.queue_expr(subject_id); }
         if progress_idx_base || progress_from { self.queue_expr(from_id); }
         if progress_idx_base || progress_to { self.queue_expr(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.expr_types.get(&ctx.heap[id].subject).unwrap().display_name(&ctx.heap));
         debug_log!("   - Expr    type: {}", self.expr_types.get(&upcast_id).unwrap().display_name(&ctx.heap));
         let expr = &mut ctx.heap[id];
         let subject_id = expr.subject;
         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)
+        }
         let (progress_subject, progress_expr) = match &mut expr.field {
             Field::Length => {
                 let progress_subject = self.apply_forced_constraint(ctx, subject_id, &ARRAYLIKE_TEMPLATE)?;
                 let progress_expr = self.apply_forced_constraint(ctx, upcast_id, &INTEGERLIKE_TEMPLATE)?;
                 (progress_subject, progress_expr)
             },
             Field::Symbolic(field) => {
                 // Retrieve the struct definition id and field index if possible
                 // and not previously determined
                 if field.definition.is_none() {
                     // Not yet known, check if we can determine it
                     let subject_type = self.expr_types.get(&subject_id).unwrap();
                     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, field.identifier.span, format!(
                                         "Can only apply field access to structs, got a subject of type '{}'",
                                         subject_type.display_name(&ctx.heap)
+                                    )
                                 ));
                             };
                             for (field_def_idx, field_def) in struct_def.fields.iter().enumerate() {
                                 if field_def.identifier == field.identifier {
                                     // Set field definition and index
                                     field.definition = Some(type_def.ast_definition);
                                     field.field_idx = field_def_idx;
                                     break;
+                                }
+                            }
                             if field.definition.is_none() {
                                 let field_span = field.identifier.span;
                                 let ast_struct_def = ctx.heap[type_def.ast_definition].as_struct();
                                 return Err(ParseError::new_error_at_span(
                                     &ctx.module.source, field_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);
@@ @@ -1920,197 +1905,195 @@ impl PassTyping { @@
                         Err(()) => {
                             return Err(ParseError::new_error_at_span(
                                 &ctx.module.source, field.identifier.span, format!(
                                     "Can only apply field access to structs, got a subject of type '{}'",
                                     subject_type.display_name(&ctx.heap)
+                                )
                             ));
+                        }
+                    }
+                }
                 // If here then field definition and index are known, and the
                 // initial type (based on the struct's definition) has been
                 // applied.
                 // Check to see if we can infer anything about the subject's and
                 // the field's polymorphic variables
                 let poly_data = self.extra_data.get_mut(&upcast_id).unwrap();
                 let mut poly_progress = HashSet::new();
                 // Apply to struct's type
                 let signature_type: *mut _ = &mut poly_data.embedded[0];
                 let subject_type: *mut _ = self.expr_types.get_mut(&subject_id).unwrap();
                 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.insert(subject_id);
+                }
                 // Apply to field's type
                 let signature_type: *mut _ = &mut poly_data.returned;
                 let expr_type: *mut _ = self.expr_types.get_mut(&upcast_id).unwrap();
                 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() {
                         self.expr_queued.insert(parent_id);
+                    }
+                }
                 // Reapply progress in polymorphic variables to struct's type
                 let signature_type: *mut _ = &mut poly_data.embedded[0];
                 let subject_type: *mut _ = self.expr_types.get_mut(&subject_id).unwrap();
                 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 _ = self.expr_types.get_mut(&upcast_id).unwrap();
                 let progress_expr = Self::apply_equal2_polyvar_constraint(
                     poly_data, &poly_progress, signature_type, expr_type
                 );
                 (progress_subject, progress_expr)
+            }
         };
         if progress_subject { self.queue_expr(subject_id); }
         if progress_expr { self.queue_expr_parent(ctx, upcast_id); }
         debug_log!(" * After:");
         debug_log!("   - Subject type [{}]: {}", progress_subject, self.expr_types.get(&subject_id).unwrap().display_name(&ctx.heap));
         debug_log!("   - Expr    type [{}]: {}", progress_expr, self.expr_types.get(&upcast_id).unwrap().display_name(&ctx.heap));
         Ok(())
+    }
     fn progress_literal_expr(&mut self, ctx: &mut Ctx, id: LiteralExpressionId) -> Result<(), ParseError> {
         let upcast_id = id.upcast();
         let expr = &ctx.heap[id];
         debug_log!("Literal expr: {}", upcast_id.index);
         debug_log!(" * Before:");
         debug_log!("   - Expr type: {}", self.expr_types.get(&upcast_id).unwrap().display_name(&ctx.heap));
         let progress_expr = match &expr.value {
             Literal::Null => {
                 self.apply_forced_constraint(ctx, upcast_id, &MESSAGE_TEMPLATE)?
             },
             Literal::Integer(_) => {
                 self.apply_forced_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)?;
                 todo!("check character literal type inference");
             },
             Literal::String(_) => {
                 self.apply_forced_constraint(ctx, upcast_id, &STRING_TEMPLATE)?;
                 todo!("check string literal type inference");
             },
             Literal::Struct(data) => {
                 let extra = self.extra_data.get_mut(&upcast_id).unwrap();
                 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 signature_type: *mut _ = &mut extra.embedded[field_idx];
                     let field_type: *mut _ = self.expr_types.get_mut(&field_expr_id).unwrap();
                     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.insert(field_expr_id);
+                    }
+                }
                 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 _ = self.expr_types.get_mut(&upcast_id).unwrap();
                 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() {
                         self.expr_queued.insert(parent_id);
+                    }
+                }
                 // 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() {
                     debug_assert_eq!(field_idx, data.fields[field_idx].field_idx, "confusing, innit?");
                     let signature_type: *mut _ = &mut extra.embedded[field_idx];
                     let field_expr_id = data.fields[field_idx].value;
                     let field_type: *mut _ = self.expr_types.get_mut(&field_expr_id).unwrap();
                     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.insert(field_expr_id);
+                    }
+                }
                 // For the return type
                 let signature_type: *mut _ = &mut extra.returned;
                 let expr_type: *mut _ = self.expr_types.get_mut(&upcast_id).unwrap();
                 let progress_expr = Self::apply_equal2_polyvar_constraint(
                     extra, &poly_progress, signature_type, expr_type
                 );
                 progress_expr
             },
             Literal::Enum(_) => {
                 let extra = self.extra_data.get_mut(&upcast_id).unwrap();
                 for _poly in &extra.poly_vars {
                     debug_log!(" * Poly: {}", _poly.display_name(&ctx.heap));
@@ @@ -2410,999 +2393,1048 @@ impl PassTyping { @@
             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 {
                     self.expr_queued.insert(*other_expr);
+                }
+            }
             // 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
                 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) {
                     SingleInferenceResult::Modified => {
                         for other_expr in &link_data.used_at {
                             self.expr_queued.insert(*other_expr);
+                        }
                     },
                     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.expr_types.get(&upcast_id).unwrap().display_name(&ctx.heap));
         Ok(())
+    }
     fn queue_expr_parent(&mut self, ctx: &Ctx, expr_id: ExpressionId) {
         if let ExpressionParent::Expression(parent_expr_id, _) = &ctx.heap[expr_id].parent() {
             self.expr_queued.insert(*parent_expr_id);
+        }
+    }
     fn queue_expr(&mut self, expr_id: ExpressionId) {
         self.expr_queued.insert(expr_id);
+    }
     /// Applies a forced type constraint: the type associated with the supplied
     /// expression will be molded into the provided "template". The template may
     /// be fully specified (e.g. a bool) or contain "inference" variables (e.g.
     /// an array of T)
     fn apply_forced_constraint(
         &mut self, ctx: &mut Ctx, expr_id: ExpressionId, template: &[InferenceTypePart]
     ) -> Result<bool, ParseError> {
         debug_assert_expr_ids_unique_and_known!(self, expr_id);
         let expr_type = self.expr_types.get_mut(&expr_id).unwrap();
         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) {
             SingleInferenceResult::Modified => Ok(true),
             SingleInferenceResult::Unmodified => Ok(false),
             SingleInferenceResult::Incompatible => Err(
                 self.construct_template_type_error(ctx, expr_id, template)
+            )
+        }
+    }
     fn apply_forced_constraint_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
         ) {
             SingleInferenceResult::Modified => Ok(true),
             SingleInferenceResult::Unmodified => Ok(false),
             SingleInferenceResult::Incompatible => Err(()),
+        }
+    }
     /// 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> {
         debug_assert_expr_ids_unique_and_known!(self, arg1_id, arg2_id);
         let arg1_type: *mut _ = self.expr_types.get_mut(&arg1_id).unwrap();
         let arg2_type: *mut _ = self.expr_types.get_mut(&arg2_id).unwrap();
         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<usize>,
+        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: cannot mutually infer the same types
         //         polymorph_data containers may not be modified
         debug_assert_ptrs_distinct!(signature_type, expression_type);
         // 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].span();
             let (span_name, span) = match expr_id {
                 Some(expr_id) => ("argument's", ctx.heap[expr_id].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_body_marker,
+                signature_type.has_marker,
                 "made progress on signature type, but it doesn't have a marker"
             );
-            for (poly_idx, poly_section) in signature_type.body_marker_iter() {
+            for (poly_idx, poly_section) in signature_type.marker_iter() {
                 let polymorph_type = &mut polymorph_data.poly_vars[poly_idx];
                 match Self::apply_forced_constraint_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<usize>,
+        polymorph_data: &ExtraData, _polymorph_progress: &HashSet<u32>,
         signature_type: *mut InferenceType, expr_type: *mut InferenceType
     ) -> bool {
         // Safety: all pointers should be distinct
-        //         polymorph_data contains may not be modified
+        //         polymorph_data containers may not be modified
         debug_assert_ptrs_distinct!(signature_type, expr_type);
         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_body_marker(seek_idx) {
+        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];
                 let modified_at_marker = Self::apply_forced_constraint_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
             ) {
                 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 expression IDs are always distinct, and we do not modify
         //  the container
         debug_assert_expr_ids_unique_and_known!(self, expr_id, arg1_id, arg2_id);
         let expr_type: *mut _ = self.expr_types.get_mut(&expr_id).unwrap();
         let arg1_type: *mut _ = self.expr_types.get_mut(&arg1_id).unwrap();
         let arg2_type: *mut _ = self.expr_types.get_mut(&arg2_id).unwrap();
         // 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 arg1_type: *mut _ = self.expr_types.get_mut(&last_arg_id).unwrap();
             let arg2_type: *mut _ = self.expr_types.get_mut(next_arg_id).unwrap();
             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(arg1_type, 0, arg2_type, 0)
+                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_type: *mut _ = self.expr_types.get_mut(args.last().unwrap()).unwrap();
         for arg_idx in 0..last_lhs_progressed {
             let arg_type: *mut _ = self.expr_types.get_mut(&args[arg_idx]).unwrap();
             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(_) | EP::Expression(_, _) =>
             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]),
         };
         match self.expr_types.entry(expr_id) {
             Entry::Vacant(vacant) => {
                 vacant.insert(inference_type);
         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,
             },
             Entry::Occupied(mut preexisting) => {
                 // We already have an entry, this happens if our parent fixed
                 // our type (e.g. we're used in a conditional expression's test)
                 // but we have a different type.
                 let old_type = preexisting.get_mut();
                 if let SingleInferenceResult::Incompatible = InferenceType::infer_subtree_for_single_type(
                     old_type, 0, &inference_type.parts, 0
                 ) {
                     return Err(self.construct_expr_type_error(ctx, expr_id, expr_id))
+                }
             Expression::Select(_) => true,
             _ => false,
         };
         debug_assert!(!(needs_extra_data && needs_var_data)); // obvious, but for future changes
         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.var_or_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
             ) {
                 return Err(self.construct_expr_type_error(ctx, expr_id, expr_id));
+            }
             debug_assert!((infer_expr.var_or_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].var_or_extra_data_idx;
         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
+        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);
+                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.insert(call_id.upcast(), ExtraData {
+        self.extra_data[extra_data_idx as usize] = ExtraData{
             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].var_or_extra_data_idx;
         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()));
+        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::MarkerBody(poly_var_idx));
             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.insert(lit_id.upcast(), ExtraData{
+        self.extra_data[extra_data_idx as usize] = ExtraData{
             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].var_or_extra_data_idx;
         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()));
+        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::MarkerBody(poly_var_idx));
             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.insert(lit_id.upcast(), ExtraData{
+        self.extra_data[extra_data_idx as usize] = ExtraData{
             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].var_or_extra_data_idx;
         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()));
+        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::MarkerBody(poly_var_idx));
             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.insert(lit_id.upcast(), ExtraData{
+        self.extra_data[extra_data_idx as usize] = ExtraData{
             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
     ) {
         use InferenceTypePart as ITP;
         // Retrieve relevant data
         let expr = &ctx.heap[select_id];
         let extra_data_idx = self.expr_types[expr.unique_id_in_definition as usize].var_or_extra_data_idx;
         debug_assert!(extra_data_idx != -1, "initial select polymorph data, but no preallocated ExtraData");
         let field = expr.field.as_symbolic();
         let definition_id = field.definition.unwrap();
         let definition = ctx.heap[definition_id].as_struct();
         let field_idx = field.field_idx;
         // 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(definition_id, num_poly_vars));
+        struct_parts.push(ITP::Instance(definition_id, num_poly_vars as u32));
         for poly_idx in 0..num_poly_vars {
             poly_vars.push(InferenceType::new(true, false, vec![
                 ITP::MarkerBody(poly_idx), ITP::Unknown,
             ]));
             struct_parts.push(ITP::MarkerBody(poly_idx));
             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.insert(select_id.upcast(), ExtraData{
+        self.extra_data[extra_data_idx as usize] = ExtraData{
             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],
-        parser_type_in_body: bool
+        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); },
                 PTV::ArrayLike => { infer_type.push(ITP::ArrayLike); },
                 PTV::IntegerLike => { infer_type.push(ITP::IntegerLike); },
                 // 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); },
                 // 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::PolymorphicArgument(belongs_to_definition, poly_arg_idx) => {
                     let poly_arg_idx = *poly_arg_idx;
-                    if parser_type_in_body {
+                    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());
                         infer_type.push(ITP::MarkerDefinition(poly_arg_idx as usize));
                         for concrete_part in &self.poly_vars[poly_arg_idx].parts {
                             infer_type.push(ITP::from(*concrete_part));
+                        }
                     } else {
                         // Polymorphic argument has to be inferred
                         has_markers = true;
                         has_inferred = true;
-                        infer_type.push(ITP::MarkerBody(poly_arg_idx));
+                        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)
+    }
     /// 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_type = self.expr_types.get(&expr_id).unwrap();
         let arg_type = self.expr_types.get(&arg_id).unwrap();
         return ParseError::new_error_at_span(
             &ctx.module.source, expr.span(), format!(
                 "incompatible types: this expression expected a '{}'",
                 expr_type.display_name(&ctx.heap)
+            )
         ).with_info_at_span(
             &ctx.module.source, arg_expr.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_type = self.expr_types.get(&arg1_id).unwrap();
         let arg2_type = self.expr_types.get(&arg2_id).unwrap();
         return ParseError::new_error_str_at_span(
             &ctx.module.source, expr.span(),
             "incompatible types: cannot apply this expression"
         ).with_info_at_span(
             &ctx.module.source, arg1.span(), format!(
                 "Because this expression has type '{}'",
                 arg1_type.display_name(&ctx.heap)
+            )
         ).with_info_at_span(
             &ctx.module.source, arg2.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_type = self.expr_types.get(&expr_id).unwrap();
         return ParseError::new_error_at_span(
             &ctx.module.source, expr.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<(usize, &'a [InferenceTypePart], &'a [InferenceTypePart])> {
             if !type_a.has_body_marker || !type_b.has_body_marker {
         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.body_marker_iter() {
                 for (marker_b, section_b) in type_b.body_marker_iter() {
             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
+        }
         // Helpers function to retrieve polyvar name and definition name
-        fn get_poly_var_and_definition_name<'a>(ctx: &'a Ctx, poly_var_idx: usize, definition_id: DefinitionId) -> (&'a str, &'a str) {
+        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].value.as_str();
+            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_var_idx: usize, expr: &Expression) -> ParseError {
+        fn construct_main_error(ctx: &Ctx, 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, expr.definition);
                     return ParseError::new_error_at_span(
                         &ctx.module.source, expr.span, format!(
                             "Conflicting type for polymorphic variable '{}' of '{}'",
                             poly_var, func_name
+                        )
+                    )
                 },
                 Expression::Literal(expr) => {
                     let definition_id = match &expr.value {
                         Literal::Struct(v) => v.definition,
                         Literal::Enum(v) => v.definition,
                         Literal::Union(v) => v.definition,
                         _ => unreachable!(),
                     };
                     let (poly_var, type_name) = get_poly_var_and_definition_name(ctx, poly_var_idx, 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 field = expr.field.as_symbolic();
                     let (poly_var, struct_name) = get_poly_var_and_definition_name(ctx, poly_var_idx, field.definition.unwrap());
                     return ParseError::new_error_at_span(
                         &ctx.module.source, expr.span, format!(
                             "Conflicting type for polymorphic variable '{}' while accessing field '{}' of '{}'",
                             poly_var, field.identifier.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_idx, expr)
                 .with_info_at_span(
                     &ctx.module.source, expr.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_idx, expr);
                     if arg_a_idx == arg_b_idx {
                         // Same argument

Changeset was too big and was cut off... Show full diff anyway

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