.required(true)

                .takes_value(true)

                .multiple_occurrences(true)

        )

        .arg(

            Arg::new("threads")

                .long("threads")

                .short('t')

                .help("number of runtime threads")

                .default_value("1")

                .takes_value(true)

        );

    // Retrieve arguments and convert

    let app = app.get_matches();

    let input_files = app.values_of("input");

    if input_files.is_none() {

        println!("ERROR: Expected at least one input file");

        return;

    }

    let num_threads = app.value_of("threads").unwrap();

    let num_threads = match num_threads.parse::<i32>() {

        Ok(num_threads) => {

            if num_threads < 0 || num_threads > 255 {

                println!("ERROR: Number of threads must be a number between 0 and 256");

                return;

            }

            num_threads as u32

        },

        Err(err) => {

            println!("ERROR: Failed to parse number of threads\nbecause: {}", err);

            return;

        }

    };

    // Add input files to file buffer

    let input_files = input_files.unwrap();

    assert!(input_files.len() > 0); // because arg is required

    let mut builder = rw::ProtocolDescriptionBuilder::new();

    let mut file_buffer = Vec::with_capacity(4096);

    for input_file in input_files {

        print!("Adding file: {} ... ", input_file);

        let mut file = match File::open(input_file) {

            Ok(file) => file,

            Err(err) => {

                println!("FAILED (to open file)\nbecause:\n{}", err);

                return;

            }

        };

        file_buffer.clear();

        if let Err(err) = file.read_to_end(&mut file_buffer) {

            println!("FAILED (to read file)\nbecause:\n{}", err);

            return;

        }

        if let Err(err) = builder.add(input_file.to_string(), file_buffer.clone()) {

            println!("FAILED (to tokenize file)\nbecause:\n{}", err);

        }

        println!("Success");

    }

    // Compile the program

    print!("Compiling program ... ");

    let protocol_description = match builder.compile() {

        Ok(pd) => pd,

        Err(err) => {

            println!("FAILED\nbecause:\n{}", err);

            return;

        }

    };

    println!("Success");

    // Make sure there is a nameless module with a main component

    print!("Creating main component ... ");

    let runtime = rw::runtime2::Runtime::new(num_threads, protocol_description);

    if let Err(err) = runtime.create_component(b"", b"main") {

        use rw::ComponentCreationError as CCE;

        let reason = match err {

            CCE::ModuleDoesntExist => "Input files did not contain a nameless module (that should contain the 'main' component)",

            CCE::DefinitionDoesntExist => "Input files did not contain a component called 'main'",

            CCE::DefinitionNotComponent => "Input file contained a 'main' function, but not a 'main' component",

            _ => "Unexpected error"

        };

        println!("FAILED\nbecause:\n{} (raw error: {:?})", reason, err);

        return;

    }

    println!("Success");

    println!("Now running until all components have exited");

}