Developer Builds Scheme Compiler to WASM Using AI in 4 Days

Matthew Phillips built Puppy Scheme, a Scheme compiler that compiles to WebAssembly, in approximately four days with AI assistance. The project was inspired by seeing others quickly build near-production-level tools that would normally take months or years.

Key Features and Capabilities

The compiler includes:

• Support for 73% of R5RS and R7RS Scheme standards
• Support for WASI 2 and the Component Model
• Uses WASM GC (garbage collection)
• Pretty good dead-code elimination, creating small binaries
• Self-hosting capability - Puppy compiles its own source code to puppyc.wasm
• A wasmtime wrapper to create native binaries
• A website that runs on Puppy wasm in Cloudflare Workers

Performance Improvements

One night, Phillips told Claude to "grind on performance" and when he woke up, compilation time had improved from 3½ minutes down to 11 seconds.

Example Code

The project includes a component model example:

(define count 0)
(define (counter-view)
  (html
    (div (@ (class "counter"))
      (button (@ (on "click" "on_decrement")) "-")
      (span (@ (class "count")) ,(number->string count))
      (button (@ (on "click" "on_increment")) "+"))))

(define (handle-event handler)
  (cond
    ((equal? handler "on_decrement")
     (if (> count 0)
         (set! count (- count 1))))
    ((equal? handler "on_increment")
     (set! count (+ count 1)))))

Current Status

The compiler is still alpha quality, and Phillips runs into bugs frequently, so it's probably not ready for anyone other than him to use. However, he notes that "the number of features is impressive for how little time I spent on it." The project demonstrates how AI can accelerate development of complex compiler projects.

Phillips worked on this as a side project, spending most of a weekend plus an hour or two on a couple of weekday nights. He's not sure where he'll take it from here, but the project is available at puppy-scheme.org.