Chaaya

Chaaya is an R7RS Scheme implementation written in C. It is a free redesign inspired by Kaappi (Zig), not a line-by-line port. Long-term goals match Kaappi’s breadth: R7RS-small, SRFIs, FFI, fibers, LLVM native backend, WASM, LSP, and packaging — delivered in phases.

Status (v0.1.0)

Bootstrap interpreter:

• NaN-boxed values + mark-sweep GC
• Datum reader / printer
• Register bytecode VM
• Special forms: quote, if, lambda, define, set!, begin, and, or, let
• Core primitives (lists, arithmetic, equality, I/O)
• Control: call/cc, dynamic-wind, with-exception-handler, raise / raise-continuable, error
• Lists/apply/map/for-each, strings, vectors, values/call-with-values
• Ports: stdio + string ports; read / display / write take optional ports
• Kaappi-shaped CLI (features, doctor, ast, …) and linenoise REPL (chaaya>, multiline, ,help, _)

Build

Requires CMake 3.21+, a C23-capable compiler, and libc. On POSIX, the interactive REPL uses vendored linenoise (arrow keys, history).

make            # configure + build → build/chaaya
make test       # build + ctest
make run        # REPL

Or with CMake directly:

cmake -S . -B build -DCMAKE_BUILD_TYPE=Release
cmake --build build -j
ctest --test-dir build --output-on-failure

./build/chaaya                 # REPL
./build/chaaya program.scm     # run a file
./build/chaaya --version       # Chaaya Scheme v0.1.0
./build/chaaya features
./build/chaaya doctor
./build/chaaya ast program.scm

REPL history is stored in ~/.chaaya/history (or $CHAAYA_HOME/history). See docs/dev/cli.md and docs/dev/repl.md.

Example

(define (fact n)
  (if (= n 0)
      1
      (* n (fact (- n 1)))))
(fact 10)

Roadmap

Phase	Focus
0–3	Scaffold, values/GC, reader, bytecode REPL (done)
4	call/cc, dynamic-wind, exceptions (done)
5	Hygienic syntax-rules + derived forms (done)
6	R7RS libraries + portable .sld reuse from Kaappi (done)
7	Full R7RS-small surface (R7RS CTest green; kaappi-deferred compliance/smoke batches in progress)
8	IR/opts, generational GC, CLI tooling (check, expand, fmt, cache) (MVP done)
9	Portable SRFI subset + import resolution (partial: ~192 vendored under lib/srfi/)
10	Fibers + FFI + reactor + SRFI-18 MVP (done)
11	LLVM / WASM / LSP / thottam integration (MVP in progress; see backlog below)

Phase 11+ backlog

Item	Current state	Next milestones
LLVM native	Real LLVM IR emit + constant-exit lowering + chaaya_rt fallback (src/llvm_backend.c)	broader form lowering, full C ABI runtime bridge
WASM	chaaya wasm runs scripts/build-wasm.sh; host-stub / WASI CMake paths	wasm32-wasi CI matrix, browser playground binary
LSP	Diagnostics, symbols, completion, hover, definition, references (src/lsp.c, src/lsp_analysis.c)	workspace/project indexing, richer docs
Compile cache	Auto .chbc read/write + cache status|clear (src/cache.c)	import-aware caching, richer per-entry status
CLI observability	--disassemble, --timings, --gc-stats, --compile, profile/coverage/timeout/sandbox MVPs	deeper coverage of library exports, parallel test --changed
thottam	Use Kaappi's Zig thottam (docs/dev/thottam.md); not reimplemented in C	consumer docs / smoke wiring only
R7RS / deferred	R7RS CTest green; large kaappi-deferred batch wired	triage remaining Kaappi compliance/smoke files

Language-parity target (≈99% Kaappi language surface): R7RS-small + portable SRFIs. Tooling/backends continue as incremental MVP hardening.

Relationship to Kaappi

Chaaya reuses Kaappi as a behavioral reference and will vendor portable Scheme libraries where licenses allow (MIT). Bytecode, IR, and ABI are intentionally independent. Note that Kaappi’s R7RS (scheme …) libraries are built-in (not lib/scheme/*.sld); portable .sld is primarily for SRFIs and user code.

Developer docs

Contributor documentation lives in docs/dev/:

• Architecture — pipeline, values, GC, VM, layout
• Backends — LLVM --native + WASM target stub status
• C23 — language standard, C23 vs C17 features to leverage
• CLI — help shape, exit codes, stubs
• REPL — prompts, comma-commands, history
• Scheme tests — bootstrap suites, probes, deferred Kaappi/R7RS
• TODO — remaining unwired smokes, SRFI import failures, Phase 11+ backlog
• Thottam — using sibling Kaappi thottam with Chaaya

License

MIT — see LICENSE.