setup-carp

A composite GitHub Action that installs the Carp compiler and prepares a CI environment for Carp libraries.

What it does

• Uses the stack pre-installed on GitHub-hosted runners. Stack downloads the GHC version Carp's stack.yaml pins into ~/.stack/programs/ on first run.
• Optionally installs SDL2 system packages (for tests that use the SDL bindings).
• Clones carp-lang/Carp at the ref you pick and builds it with stack install.
• Puts the carp binary on PATH and exports CARP_DIR so the compiler can find its core/ sources.
• Caches ~/.stack and .stack-work keyed on the ref and stack.yaml.lock, so subsequent runs reuse the build.

Runs on ubuntu-latest and macos-latest. On custom or self-hosted runners that don't ship with stack, prepend haskell-actions/setup@v2 yourself.

Usage

Minimal library CI:

name: CI
on: [push, pull_request]

jobs:
  test:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: carpentry-org/setup-carp@v1
      - run: carp -x test/all.carp

Pinning a specific Carp version and enabling SDL:

      - uses: carpentry-org/setup-carp@v1
        with:
          carp-ref: v0.6.0
          sdl: true

Matrix across OSes:

jobs:
  test:
    strategy:
      matrix:
        os: [ubuntu-latest, macos-latest]
    runs-on: ${{ matrix.os }}
    steps:
      - uses: actions/checkout@v4
      - uses: carpentry-org/setup-carp@v1
      - run: carp -x test/all.carp

Inputs

Input	Default	Description
carp-ref	master	Git ref (branch, tag, or SHA) of the Carp compiler to build.
carp-repository	carp-lang/Carp	Source repository for Carp.
sdl	false	If true, install SDL2 system packages.
install-path	.carp-src	Workspace-relative path where Carp is cloned and built.
rewrite-git-urls	true	Rewrite git@github.com: to https://github.com/ so (load "git@...") works without an SSH key. Set to false if you have your own SSH auth configured.

Outputs

Output	Description
carp-dir	Absolute path of the Carp source directory (same as CARP_DIR).
carp-sha	Resolved commit SHA of the built compiler.
carp-version	Human-readable version string via git describe --tags --always (e.g. v0.6.0, v0.6.0-3-gabcdef).

Notes

• The first cold build takes ~5–10 minutes (Haskell). Cached runs are typically under a minute.
• For performance comparisons in CI, run Carp with --optimize so the generated C is built at -O2 rather than -O0.
• If your library depends on system libraries beyond SDL2, install them in your own step before invoking carp.

License

Apache 2.0.

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Have fun!