Everything beside this is rendered by Goeteia.
The Scheme below is compiled to WebAssembly in your browser and mounted live.
Try changing a string, or drive the spell signal. This page carries the whole compiler (goeteia.wasm, ~70 KB gzipped, cached after first load); each recompile takes ~15 ms.
The compiler is written in the Scheme subset it compiles. The self-hosted build recompiles itself and the output is byte-identical — the fixpoint is checked in CI fashion on every change, and every test runs through both stages.
Fixnums are unboxed i31refs, pairs and records are GC structs, eq? is one ref.eq. No shadow heap in JavaScript: the host supplies two byte-stream imports and nothing else.
syntax-rules and procedural syntax-case with fenders, nested ellipses and datum->syntax, running in a compile-time interpreter with hygiene by renaming.
Typed function references with a fast per-arity entry and a generic entry per closure — variadic procedures and apply are cheap, and every tail call is a return_call. A 100M-iteration loop runs in constant stack, in ~150ms.
Fixnums promote to bignums on overflow (checked inline, two bit-compares), flonums have contagion, rationals and complex are exact, and float literals are encoded to IEEE-754 by pure Scheme — so both hosts emit identical bytes.
Escape continuations ride the Wasm exception-handling proposal: capture is O(1), the normal path costs one try block, and winders unwind inner-to-outer on the way out.
(web sx) templates over fine-grained (web reactive) signals, an (web html) renderer, and a (web js) FFI that reaches straight into the host — this page is built with it.
R6RS-style (library ...) files with (import (math utils)) resolution, dependencies first; exports are advisory because unused code is pruned anyway.
$ git clone https://github.com/guenchi/Goeteia
$ cd Goeteia
$ ./run-tests.sh # every test, both compiler stages
$ ./build-self.sh # rebuild the compiler with itself
$ echo '(define (fact n) (if (zero? n) 1 (* n (fact (- n 1)))))
(fact 20)' > fact.ss
$ node rt/compile.mjs goeteia.wasm fact.ss fact.wasm
$ node rt/run.mjs fact.wasm
2432902008176640000Compiled modules run on any engine with Wasm GC and tail calls: Node 22+, current Chrome / Firefox / Safari, wasmtime. Bootstrapping from source needs Chez Scheme; the checked-in compiler wasm works without it.