A complete R7RS-small Scheme implementation with an LLVM native compiler, C FFI, OS threads, and a curated package ecosystem.
Get Started · Procedures · Ecosystem · Playground · Docs
kaappi/kaappi is the core interpreter — written in Zig, implementing every identifier from R7RS Appendix A plus all 14 standard libraries and a broad set of SRFIs. The LLVM native backend compiles Scheme to standalone binaries on AArch64/x86_64. First-class call/cc, hygienic macros, green fibers, OS threads, a stepping debugger, a profiler, and a sandbox mode are all included.
Installable via thottam, the Kaappi package manager.
| Package | What it does |
|---|---|
| kaappi-http | HTTP/1.1 client and server (pre-fork, threaded) |
| kaappi-web | Web framework — routes, middleware, JSON helpers |
| kaappi-pg | PostgreSQL client (libpq, parameterized queries, cursors) |
| kaappi-redis | Redis client (RESP2, pipelining, pub/sub) |
| kaappi-json | RFC 8259 JSON parser and serializer |
| kaappi-net | TCP/TLS networking (shared by http, redis, pg) |
| kaappi-sqlite | SQLite bindings (DB-API, parameterized queries) |
| kaappi-crypto | Cryptography (OpenSSL — hashing, HMAC, random) |
| kaappi-email | Email (MIME construction, SMTP) |
| kaappi-cli | CLI framework — arg parsing, subcommands, auto help |
Plus csv, yaml, toml, log, template, test, and bdd.
(import (scheme base) (scheme write))
(define (fib n)
(if (< n 2) n
(+ (fib (- n 1))
(fib (- n 2)))))
(display (fib 30)) ;=> 832040kaappi-examples — 12 runnable programs from beginner to advanced. Pure Scheme examples need zero setup beyond the kaappi binary.
| Example | What it does | Difficulty |
|---|---|---|
| Sorting Algorithms | Functional quicksort & merge sort with higher-order abstractions | Beginner |
| Game of Life | Conway's automaton — functional grid updates, ANSI animation | Beginner |
| Maze Solver | DFS generation & solving with immutable state | Intermediate |
| Huffman Coding | Compression with binary trees and prefix codes | Intermediate |
| Symbolic Differentiation | Symbolic calculus with AST walking and algebraic simplification | Advanced |
| Metacircular Evaluator | Scheme interpreting Scheme — the classic eval/apply loop | Advanced |
| Lazy Evaluator | Normal-order evaluation with memoizing thunks | Advanced |
| REST API | Full web server with PostgreSQL, Redis caching, JSON | Advanced |
git clone https://github.com/kaappi/kaappi-examples.git
kaappi kaappi-examples/game-of-life/app.scm demo
kaappi kaappi-examples/metacircular-evaluator/app.scm demo| macOS aarch64 | Linux x86_64 | Linux aarch64 | Linux riscv64 | WebAssembly | |
|---|---|---|---|---|---|
| Build + tests | yes | yes | yes | yes | yes |
| Native compiler | AArch64 | x86_64 | AArch64 | — | — |
GitHub Discussions — ask questions, report bugs, propose features, or say hello. Issues and PRs are open to org members; ask for an invite in Discussions when you're ready to contribute.
- Documentation — user guide, procedure reference, ecosystem docs
- Playground — browser REPL powered by
kaappi.wasm - Tour — 12-lesson guided tour with live code
- Community — how to participate
MIT License — built with Zig
