Snail-Scheme

Snail-Core is a typed functional language with Scheme syntax that compiles to WasmGC. It has structs, enums, pattern matching, typeclasses with generic instances, Koka-style effect rows with handlers, and wire types with stable schema identities. The compiler is written in Snail-Core and compiles itself; Chibi Scheme runs its source to start the first bootstrap.

(import
 (snail-core base)
 (snail-core io))

(: fibonacci (-> I64 I64))
(define (fibonacci n)
  (if (< n 2) n (+ (fibonacci (- n 1)) (fibonacci (- n 2)))))

(display (fibonacci 30))
(newline)

Getting started

nix-shell
make fetch
./snail build apps/siegework site
./snail dev apps/siegework

Compiler contributors can also inspect and execute individual source files:

./scripts/snail-tool run examples/fibonacci.sld
./scripts/snail-tool compile -o build/fibonacci.wasm examples/fibonacci.sld
./scripts/snail-tool wat examples/effects.sld
./scripts/snail-tool watch examples/fibonacci.sld   # runs it again after each edit

Chibi Scheme, Binaryen, Rust and Node 26.4 or later are required. shell.nix provides them from the nixpkgs revision CI uses, and .devcontainer/ packages the same tools for podman. Getting started covers both, other package managers and Windows, and the checks. make fetch downloads the Rust crates once; builds and tests then run offline.

Programs link with Rust scalar services and run under WASI. The first run bootstraps the compiler, which takes about a minute: Chibi runs its source once, and the compiled compiler then rebuilds itself whenever the source changes.

Siegework

Siegework is a colony game written in Snail-Core: explore a seeded map, wire an energy network across it, and destroy three nests before their attacks destroy your hub. It runs in the browser with WebGPU. Play it online, or build it:

make site
python3 -m http.server 4191 --directory apps/siegework/build/site

While you change it, ./scripts/snail-tool serve apps/siegework serves it at http://127.0.0.1:8000/, rebuilds only the libraries you edit, and relinks them into the open page, which keeps the game and the camera. ./snail dev --port 8001 apps/siegework starts the native project compiler and browser editor. It reads project.datum; saving writes disk, and one shared watcher notifies both compiler and editor, including edits made by other tools. The editor keeps highlighting, Scheme indentation, format-on-save and split panes. Builds publish fresh diagnostics with source points in saved buffers. make ide starts this service for Siegework on port 8000.

The Applications panel starts, stops and restarts named program targets. Accepted builds replace affected wanted processes; failed builds leave them running. The development workflow still needs browser bundle and durable-state reload integration. Use internal serve for the existing browser reload loop. The typed-state API remains under review.

Reading on

• The book gathers the guides below with the player's guide and tutorials; make pages builds it with the game into build/pages.
• The language chapters describe terms, types, macros and the standard library as implemented.
• The compiler architecture follows a program through the passes, linking and incremental caches.
• Projects and targets defines inert descriptions, directory outputs and artifact bundles.
• The development toolchain explains the native project service and browser editor.
• GitHub issues track open work.

Apache-2.0