fun fib(n) {
    if (n < 2) {
        return n;
    }
    return fib(n - 2) + fib(n - 1);
}

print fib(15);

An Abstract Syntax Tree (AST) generated for the program above:

What is it?

Rust implementations of Lox language as it is described in a gorgeous book Crafting Interpreters. I really recommend everyone to read it! Both fun and educational content.

Why?

This is my first Rust project, my first project connected with interpreters/languages and also my first project where I need to read Java code (I don't know the language) and port something from it. So for me this project serves 2 main purposes:

• Learn Rust and get more comfortable with it
• Get some knowledge of how computer languages actually work internally

Also I learnt some Java. At least reading it.

Structure

• benchmark — very simple benchmark for Lox implementations and comparison with some other languages
• twi — code for Tree-Walk Interpreter, as it is described in Part II of the book, and also code for custom AST visualizer that outputs nice pictures such as the one above
• bvm — Bytecode Virtual Machine, as it is described in Part III of the book

twi and bvm are implemented as self-consistent and completely independent Rust crates. benchmark is a set of independent scripts on various languages.

Current status of the project

Unfinished. I plan to do more things. For example:

• Fix the way twi deals with environments, so the execution speed and some bugs will be fixed
• Finish bvm implementation, as it does not support OOP yet

I also have some ideas like adding new datatypes (arrays, hash maps) and other features.