ballercat/walt

★ 4,642JavaScriptAudience · developerComplexity · 3/5Setup · moderate

Mindmap

mindmap
  root((Walt))
    What It Does
      JS-like syntax
      Compiles to WebAssembly
      No LLVM needed
    Input
      Typed JS subset
      Familiar syntax
      Type annotations
    Output
      WebAssembly binary
      Browser-ready
    Use Cases
      Games
      Real-time compute
      Web VR and AR
    Integration
      Webpack plugin
      Existing JS projects

mindmap root((Walt)) What It Does JS-like syntax Compiles to WebAssembly No LLVM needed Input Typed JS subset Familiar syntax Type annotations Output WebAssembly binary Browser-ready Use Cases Games Real-time compute Web VR and AR Integration Webpack plugin Existing JS projects

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Things people build with this

USE CASE 1

Write browser performance-critical code in familiar typed JavaScript syntax that compiles to WebAssembly without learning C or Rust

USE CASE 2

Add a WebAssembly module to an existing webpack project for real-time computation or game logic

USE CASE 3

Build a web library that runs expensive operations in WebAssembly while keeping the rest of the codebase in standard JavaScript

USE CASE 4

Experiment with WebAssembly output for web VR, AR, or simulation that needs near-native browser speed

Tech stack

JavaScriptWebAssembly

Getting it running

Difficulty · moderate Time to first run · 30min

Alpha software, not production-ready, integrates via webpack plugin, so an existing webpack setup is assumed.

In plain English

Walt is an experimental compiler that lets JavaScript developers write code that compiles directly to WebAssembly, a low-level binary format that browsers can run at near-native speed. The problem it addresses is that writing WebAssembly directly requires either learning a systems programming language like C, C++, or Rust, or working with a terse and difficult text format called WAT. Walt aims to remove that barrier by letting you write something that looks almost exactly like typed JavaScript instead. The syntax Walt accepts is a subset of JavaScript with explicit types added, similar to TypeScript but more constrained. You write functions using familiar JavaScript structure, declare types for parameters and return values, and the compiler turns that into a WebAssembly binary that browsers can load and run. The project's example shows a recursive Fibonacci function written in Walt that looks identical to JavaScript except for the type annotations. No external binary tools like LLVM or Emscripten are required, since the compiler itself is written entirely in JavaScript. Walt integrates with webpack, the common JavaScript bundling tool, so it fits into an existing web project build process without a major change to your setup. A browser-based explorer on the project's website lets you try it without any installation. The stated goal is to make WebAssembly practical for front-end web developers who are not familiar with systems languages. The README notes use cases like web libraries that need better performance, games, real-time computation, and web VR and AR. The project is marked as alpha, meaning it is experimental and not yet production-ready. A roadmap and a quick-start guide are available on the project wiki. Contributions are welcomed.

Copy-paste prompts

Prompt 1

I want to write a WebAssembly function using Walt that computes Fibonacci numbers faster than JavaScript. Show me the Walt syntax for the function, how to compile it, and how to call it from a browser page

Prompt 2

How do I integrate a Walt-compiled WebAssembly module into a webpack project? Show me the webpack config and how to import and call the exported functions from JavaScript

Prompt 3

I have a computationally heavy algorithm in JavaScript. Show me how to rewrite it in Walt syntax with type annotations and export it as a WebAssembly module my main JS code can call

Prompt 4

What are the current limitations of Walt compared to writing WebAssembly in C or Rust, and when does it make sense to use Walt instead of Emscripten?

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