nathsou / Elox

Interpreter for a superset of Crafting Interpreter's lox language

Elox

Elox for Extended-lox, is a superset of the lox toy language from Bob Nystrom's book Crafting Interpreters.

It is an interpreted (both in a VM or directly by walking the AST) or compiled (to WASM), dynamically typed, objected oriented programming language.

You can test it here

Its main additions to lox are :

• Native Arrays
• String concatenation of any variable types allowed
• Modulo '%' operator available
• Usual assignment shorthands: +=, -=, ++, --, *=, /=, %=
• Default valued function parameters
• Rest parameters
• Anonymous functions allowed

Running

Elox is written in Rust and can thus target your computer's architecture and WebAssembly.

Furthermore, an Elox to wasm compiler is in development

Compiling and running

In the project folder:

$ cargo run --release --bin [elox | vm | wasm] [file.elox]

Compiling to WebAssembly

Compiling an elox program to wasm

Elox can target wasm directly, it uses the VM compiled bytecode as an intermediate representation which is then translated to WebAssembly

$ cargo run --release --bin wasm [file.elox]

this command produces a file named out.wasm which can be run with :

$ node run_wasm.js

Compiling the project to wasm

Using wasm-pack in the project folder:

$ wasm-pack build

The demo website using the compiled wasm module can be run using:

$ cd web
$ npm run start

Todo

• Arrow functions
• standard library
• Implement traits
• Write a compiler targetting wasm directly
• Optional type annotations used by a static type checker
• Function overloading
• 'const' keyword
• Replace 'nil' with Option<T> or other? => match and enums?
• bundler to import other elox files
• extern code execution (C or JS)

Examples

Demos are available in the /demos folder and can be run online.

// Pseudo Random Number Generator
class PRNG {
  init(seed = clock() * 1000) {
    this.a = 25214903917;
    this.c = 11;
    this.m = 281474976710656;
    this.seed = seed;
  }

  next() {
    this.seed = (this.a * this.seed + this.c) % this.m;
    return this.seed / this.m;
  }
}
 
var prng = PRNG();
var nums = [];

for (var i = 0; i < 10; i++) {
   nums.push(prng.next());
}

print nums;