Hatch Compiler - Bird Language Compiler

A compiler implementation for the Bird programming language, written in OCaml using the Dune build system. This project compiles Bird language source files (.bird extension) into executable binaries.

Features

• Arithmetic Operations: Support for basic arithmetic expressions with proper operator precedence
• Variable Bindings: let...in expressions for local variable binding
• First-Class Functions: Functions are values that can be passed, returned, and stored (OCaml-like semantics)
• Control Flow: Conditional expressions with if statements
• Type Checking: Built-in type predicates (isbool, isint) and comparison operators
• Error Handling: Comprehensive error reporting and runtime error handling
• Garbage Collection: Integrated garbage collector for memory management

Project Structure

src/
├── compiler/        # Core compiler implementation
│   ├── assembly.ml  # Assembly code generation
│   ├── builder.ml   # Build orchestration
│   ├── compiler.ml  # Main compilation logic
│   └── ...
├── language/        # Language parsing and AST definitions
│   ├── asts.ml      # Abstract syntax tree definitions
│   ├── lexer.mll    # Lexical analyzer
│   ├── parser.mly   # Parser grammar
│   └── ...
├── main/            # Entry point
│   └── hatch.ml     # Main executable
└── tests/           # Test suite
    └── tests.ml

test_code/           # Test programs organized by feature
├── arithmetic.bird  # Basic arithmetic
├── let1.bird       # Variable binding
├── bluebird/       # Control flow tests
├── cardinal/       # Error handling tests  
├── dove/           # Function definition tests
└── ...

Building and Running

Prerequisites

• OCaml (with Dune build system)
• Make (optional, for convenience)

Build

make build
# OR
dune build

Run Compiler

./hatch <filename.bird>

Run Tests

make test
# OR
./tests

Bird Language Syntax

Basic Arithmetic

3 * (1 + (4 - 2) - (3 * 2))

Variable Binding

let x = 3 in 4 + x

Function Definition

def f x = 
  x + 1
end

f 5

Conditional Expressions

if x > 0 then x else 0

Test Organization

The test suite is organized by language features:

• Basic: Arithmetic and basic expressions
• Bluebird: Control flow and conditionals
• Cardinal: Error handling and edge cases
• Dove: Function definitions and calls
• Eagle/Falcon/Gull: Advanced language features

Development

The compiler is structured as a traditional multi-pass compiler:

1. Lexing: Tokenization of source code
2. Parsing: Construction of abstract syntax tree
3. Well-formedness: Static analysis and type checking
4. Compilation: Code generation to assembly
5. Assembly: Final executable generation

The project uses OCaml's Menhir parser generator and includes comprehensive error handling throughout the compilation pipeline.

Credits

This compiler project was developed as part of CS75: Compilers at Swarthmore College, taught by Professor Zachary Palmer. The project follows a progressive series of language implementations, building from basic arithmetic expressions to a full functional programming language with garbage collection.