ludic/CONTRIBUTING.md

Contributing to Ludic

Thanks for your interest in Ludic — an AoT-compiled game language with an ECS core, a deterministic fixed-point runtime, and a native 2D backend. This guide covers the unusual bit: Ludic is self-hosted, so the compiler, the runtime, and the tooling are all written in Ludic and built by Ludic.

Prerequisites

• clang (or another C compiler) — used once to assemble the checked-in LLVM-IR seed into the first ludicc, and thereafter only to assemble IR and link. No C is generated in a build.
• LLVM (for the web/wasm target: brew install llvm lld).
• macOS for the windowed Cocoa backend; headless PPM rendering works anywhere.

First build (bootstrap)

From a clean checkout, one line lifts the toolchain off the seed:

clang selfhost/ludicc.seed.ll -o bin/ludicc && bin/ludicc tools/x/main.ludic -o bin/x

That gives you bin/x, the Ludic task runner that replaces every build/test shell script in the repo. From then on it builds everything — including itself:

bin/x build          # rebuild the whole toolchain into bin/ (ludicc, ludic, x, ludic-fmt, ludic-lsp)
bin/x help           # list every command

Always run x from the repository root, so assets/ and selfhost/ resolve.

The development loop

When you change the compiler or runtime, prove the self-hosting fixpoint still holds before you push:

bin/x reseed          # regenerate selfhost/ludicc.seed.ll after a compiler change
bin/x bootstrap-cfree # rebuild the compiler from the seed with NO C compiler in the loop
bin/x test            # the full regression suite

Other useful targets:

bin/x app <file.ludic> [--headless]   # compile a program to a native app in build/
bin/x selfhost-test                   # correctness + bootstrap fixpoints
bin/x test-tools                      # the editor-toolchain suite (ludic-fmt, ludic-lsp)
bin/x clean                           # remove build/, out.ppm and stray artifacts

Adding to the standard library

The stdlib lives in the runtime (runtime/) and is surfaced as namespaces (Math.*, Crypto.*, DateTime.*, Screen.*, …). When you add a symbol:

1. Implement it in the runtime / emitter as appropriate.
2. Document it: add one Markdown file per symbol under docs/language/<namespace>/ and register its id in tools/docgen/inventory.json. Each documented namespace gets exactly one directory (the docs check enforces this).
3. Add or extend an example under examples/ and a case in the test suite.
4. Run python3 tools/docgen/gen.py && python3 tools/docgen/check.py — the check fails if any inventory symbol lacks a page or is still seed text.

Conventions

• Commits: Conventional Commits — type(scope): summary, with an optional ! before the colon for a breaking change. Keep the summary imperative and under ~72 chars. The types in use:

  type	for
  feat	a new user-facing capability (a stdlib namespace, a language feature)
  fix	a bug fix
  refactor	a change that neither fixes a bug nor adds a feature
  perf	a performance improvement
  docs	documentation only (docs/, README, comments)
  test	tests only
  build	the build/bootstrap machinery (seed, bin/x, linking)
  ci	CI workflows under .forgejo/
  style	formatting/whitespace, no behaviour change
  chore	routine housekeeping with no other bucket
  revert	reverts a previous commit

  Common scopes: stdlib, lang, emit, runtime, tooling, docs, repo. Reference the issue you close with a Closes #NN trailer.

• Enforcement: the hooks in tools/git-hooks/ enforce this locally, and the commit-lint CI job is the backstop. Turn the hooks on once, per clone:

  git config core.hooksPath tools/git-hooks
  

  That activates the commit-msg hook (rejects a non-conforming summary) and the pre-commit hook (rejects unformatted Ludic). Both read the same rules CI does, so a green local commit is a green CI run.

• Formatting: ludic-fmt is the source of truth (2-space indent, LF, UTF-8); the repo .editorconfig mirrors it. Run bin/ludic-fmt -w on files you touch. The contract CI enforces is idempotence — ludic-fmt re-run on its own output is a no-op — which leaves deliberate hand alignment in place; it is not a blanket fmt(x) == x.

• Code structure: one job per file. Split large files by concern into subfolders rather than growing a single 500+-line module (see how selfhost/ and runtime/ are organised).

• Language of the toolchain: new runtime and tooling are written in Ludic, not C, Python, or JS. The only non-Ludic pieces are the LLVM-IR seed (selfhost/ludicc.seed.ll), the hand-written runtime/native/cocoa.ll / runtime/web/wasm.ll shims, and the legacy Python docgen (being ported).

Git history

The log has two eras: the pre-self-hosting Phase Nx: … / Merge Phase Nx: … commits, and the Conventional Commits used since. Decision: the old Phase history stays as-is. Rewriting already-pushed history (filter-repo/rebase) is destructive and non-reversible for anyone who has cloned, and it buys little — so we do not rewrite it. The convention is enforced going forward by the hook and the commit-lint job (both skip merge commits, so the old merges never trip it).

When the versioning work lands (issue #33), the first release tag doubles as a clean v0 baseline that brackets the Phase-era prefix — the safe, non-destructive version of "tidy the history" without touching a single commit.

Pull requests

• Base your branch on main.
• Ensure bin/x test (and bin/x bootstrap-cfree for compiler/runtime changes) pass, and that ludic-fmt leaves your files unchanged.
• Fill in the PR template checklist. Reference the issue you close with Closes #NN in the description or a commit message.

Reporting issues

Use the templates under .forgejo/issue_template/: a bug report, a proposal (new stdlib/language surface), or a cleanup/DX task. Choose the one that fits and fill in the sections.

By participating you agree to the Code of Conduct.