monkey-rs

Rust Interpreter and Compiler for Monkey Programming Language

Based on the books Writing An Interpreter In Go and Writing A Compiler In Go by Thorsten Ball

Built as a learning exercise to better understand the Rust and Go programming languages and how interpreters and compilers work

Usage

Requires Rust to be installed

REPL

$ cargo run --release
>> let add = fn(x, y) { x + y };
>> add(1, 2);
3

File Loading

$ cargo run --release -- --file=examples/fibonacci.monkey
[0, 1, 1, 2, 3, 5, 8, 13, 21, 34 ...]

Use the -i or --interpreter flag to run in interpreter mode instead of compiler mode for REPL and File Loading

Benchmarking

Compare the performance of the interpreter and compiler modes

$ cargo run --release -- --benchmark --file=examples/fibonacci_benchmark.monkey
Parsing took: 18.791µs
Evaluation (interpreter) took: 42.488771428s
Compilation took: 7.754µs
Execution (VM) took: 5.539178683s

The compiler is almost 8x faster than the interpreter for this example!

Features

monkey-rs aims to be a fully featured interpreter and compiler for the Monkey Programming Language with additional features inspired by other languages such as Python.

Features progress is tracked below:

• Language features from Monkey Programming Language
  • C-like syntax
  • Primitive Types (integers, booleans, strings, arrays, hash maps)
  • Arithmetic Expressions
  • Let and return statements
  • Conditionals
  • Functions (first-class, higher-order, closures)
  • Built-in functions (len, puts, push, etc.)
• Additional language features
  • Better string parsing - character escaping and error handling
  • String indexing (ex: "hello"[4] -> 4)
  • Python-like string and array slicing (ex: [1, 2, 3, 4][1:-1] -> [2, 3])
• REPL and File Loading
• Interpreter
  • Lexer / Tokenizer
  • Pratt Parser
  • Abstract Syntax Tree
  • Evaluator
• Bytecode Compiler
  • Conversion from AST to Bytecode
  • File Output
• Virtual Machine
  • Stack-based VM
  • Bytecode Interpreter
• Unit Tests

The only major missing feature is file output for the bytecode compiler - this is currently a work in progress. Perhaps new language features and performance improvements could be added in the future as well.