build.yml

name: build

concurrency:
  group: ${{ github.workflow }}-${{ github.head_ref || github.run_id }}
  cancel-in-progress: true

on:
  pull_request:
    branches:
      - main
  schedule:
    - cron: 0 0 * * *

jobs:
  build:
    name: GHC ${{ matrix.ghc-version }} on ${{ matrix.os }}
    runs-on: ${{ matrix.os }}
    strategy:
      fail-fast: false
      matrix:
        os: [ubuntu-latest]
        ghc-version:
          - '8.10'
          - '9.0'
          - '9.2'
          - '9.4'
          - '9.6'
          - '9.8'

    steps:
      - uses: actions/checkout@v3

      - name: Set up GHC ${{ matrix.ghc-version }}
        uses: haskell/actions/setup@v2
        id: setup
        with:
          ghc-version: ${{ matrix.ghc-version }}
          # Defaults, added for clarity:
          cabal-version: 'latest'
          cabal-update: true

      - name: Configure the build
        run: |
          cabal configure --enable-tests --enable-benchmarks --disable-documentation
          cabal build --dry-run
        # The last step generates dist-newstyle/cache/plan.json for the cache key.

      - name: Restore cached dependencies
        uses: actions/cache/restore@v3
        id: cache
        env:
          key: ${{ runner.os }}-ghc-${{ steps.setup.outputs.ghc-version }}-cabal-${{ steps.setup.outputs.cabal-version }}
        with:
          path: ${{ steps.setup.outputs.cabal-store }}
          key: ${{ env.key }}-plan-${{ hashFiles('**/plan.json') }}
          restore-keys: ${{ env.key }}-

      - name: Install dependencies
        run: cabal build all --only-dependencies

      # Cache dependencies already here, so that we do not have to rebuild them should the subsequent steps fail.
      - name: Save cached dependencies
        uses: actions/cache/save@v3
        # Caches are immutable, trying to save with the same key would error.
        if: ${{ steps.cache.outputs.cache-primary-key != steps.cache.outputs.cache-matched-key }}
        with:
          path: ${{ steps.setup.outputs.cabal-store }}
          key: ${{ steps.cache.outputs.cache-primary-key }}

      - name: Build
        run: cabal build all

      - name: Run tests
        run: cabal test all

      - name: Check cabal file
        run: cabal check

      - name: Build documentation
        run: cabal haddock all

  success:
    needs: build
    runs-on: ubuntu-latest
    if: always() # this is required as GitHub considers "skipped" jobs as "passed" when checking branch protection rules

    steps:
      - run: false
        if: needs.build.result != 'success'

      - uses: actions/checkout@v3
      - name: Check for trailing whitespace
        run: '! git grep -I "\s\+$"'
      - run: curl -sSL https://raw.githubusercontent.com/sol/hpack/main/get-hpack.sh | bash
      - run: hpack && git diff --color --exit-code