A bytecode VM-based interpreter inspired from the Lox language, built using Zig.

Language Overview

Getting Started

Hello World

print "hello world\n";

Expressions

let a = 10 * (2 + 3) - 7;
print a;
print "\n";

let b = !(true == false);
let c = ((3 + 4) * 5) - (6 / 2);

print b;
print "\n";
print c;
print "\n";

Locals

fn main() {
    let a = "outer a\n";
    {
        let a = "inner a\n";
        print a;
    }
    print a;
}

main();

Control flow

fn main() {
    for (let i = 1; i < 10; i = i + 1) {
        for (let j = 1; j <= i; j = j + 1) {
            print "*";
        }
        print "\n";
    }
}

main();

Functions

fn fib(n) {
    if n < 2 { return n; }
    return fib(n - 1) + fib(n - 2);
}
// clock() is a native function
let start = clock();
let result = fib(3);
print result; print "\n";
print "took: "; print clock() - start; print " miliseconds\n";

Closure

fn outer() {
  let x = "local x\n";
  fn inner() {
    print x;
  }
  inner();
}
let x = "global x\n";
outer();

Language Design

The language, tentatively named wlox, is designed to be a dynamically typed programming language with support for garbage collection, functions, and closures. Inspired by the Lox programming language, wlox aims to provide a modern and intuitive syntax while offering powerful features.

1. Dynamic Typing: In wlox, variables are dynamically typed, meaning their types are determined at runtime rather than compile time. This allows for greater flexibility and ease of use, as variables can hold values of any type without explicit type annotations.

2. Garbage Collection: To manage memory efficiently and prevent memory leaks, wlox incorporates automatic garbage collection. This feature relieves developers from manual memory management tasks, allowing them to focus on writing clean and concise code.

3. Functions and Closures: Functions play a central role in wlox, serving as first-class citizens that can be assigned to variables, passed as arguments, and returned from other functions. Closures, a powerful concept in functional programming, are fully supported, enabling the creation of lexically scoped function closures.

The language design of wlox aims to strike a balance between simplicity and expressiveness while also exploring the features of most modern programming languages.

Future Enhancements

To ensure continuous improvement and adaptability, the following future enhancements are planned for Wlox:

• Advanced Language Features: Add support for classes, methods, and objects to expand the language's capabilities.
• Debugging Tools: Integrate debugging features in the UI, such as breakpoints and step-through execution, to aid in code troubleshooting.
• Performance Improvements: Optimize the interpreter for better execution speed and memory usage, enhancing overall performance.
• Browser Compatibility: Ensure consistent functionality and performance across various web browsers to reach a wider audience.
• User Interface Enhancements: Improve the UI for a more intuitive and responsive user experience.
• Detailed Documentation: Provide comprehensive documentation, including installation instructions, user guides, and developer resources, to facilitate easier adoption and usage.

Development

This project uses devbox to manage its development environment.

Install devbox:

curl -fsSL https://get.jetpack.io/devbox | bash

Start the devbox shell:

devbox shell

Run a script in the devbox environment:

devbox run <script>

Scripts

Scripts are custom commands that can be run using this project's environment. This project has the following scripts:

• wlox
• wlox-verbose
• www-nginx
• www-python
• zlox
• zlox-verbose
• docs

Documentation

You can build the autogenerated Zig documentation on your local machine with the docs script.

First, make sure you are inside the devbox shell. Then run:

devbox run docs

Now you can view the documentation in your browser at http://localhost:8000, just make sure the 8000 port isn't already being used

Packages

• [email protected] (for building the Zig stuff)
• [email protected] (for LSP support)
• typescript@latest (for LSP support)
• nginx@latest (for web server)
• python@latest (for web server)
• nodePackages.npm@latest (packages for the web repl)

Script Details

devbox run npm

Install the npm packages required for the REPL. This should be run at least once, before launching the web servers.

pushd www/
npm install
popd

devbox run wlox

Build the wasm file and start the Python web server. Open the URL http://localhost:8000 in your browser.

zig build -Dtarget=wasm32-freestanding -Doptimize=ReleaseFast wlox
devbox run www-python

devbox run wlox-verbose

Build the wasm file with verbose output.

zig build -Dverbose -Dprint-bytecode -Dtarget=wasm32-freestanding -Doptimize=ReleaseFast wlox

devbox run www-python

Run a simple web server in Python to serve the website files. The console output should inform about which port the server is running on.

python -m http.server -d www/

devbox run www-nginx

Run the Nginx web server to serve the website files. The port is determined by the NGINX_WEB_PORT environment variable.

devbox services up

devbox run zlox

Build the command-line interpreter.

zig build -Doptimize=ReleaseFast

devbox run zlox-verbose

Build the command-line interpreter with verbose output

zig build -Dverbose -Dprint-bytecode -Ddisplay-stack

devbox run docs

Build the local documentation and start the web server to view the documentation.

zig build docs
python -m http.server -d ./zig-out/docs/