The readme could do with an example of building and testing a cabal project

[expipiplus1]

Including caching and all that.

[jonathanknowles]

@expipiplus1

I've put together an example project here, which might be useful as a guide:
https://github.com/jonathanknowles/haskell-example

It includes caching of build products, and also publishes haddock documentation to GitHub pages.

Let me know if I can provide any further info!

[andreasabel]

I applied to update the official Haskell starter action template:

• Update ci/haskell to maintained action haskell/actions/setup actions/starter-workflows#1937
  This would be the suggested default workflow:

# Haskell CI using Cabal via haskell/action/setup.
# Build and test a Haskell project using standard cabal commands.
# Author (2022-02-13): Andreas Abel

# This workflow uses actions that are not certified by GitHub.
# They are provided by a third-party and are governed by
# separate terms of service, privacy policy, and support
# documentation.

name: Haskell CI

on:
  push:
    branches: [ $default-branch ]
  pull_request:
    branches: [ $default-branch ]

permissions:
  contents: read

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

        include:
        - os: windows-latest
          ghc-version: '9.4'
        - os: macos-latest
          ghc-version: '9.4'

    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: Installed minor versions of GHC and Cabal
      shell: bash
        # bash is default in Linux, but needed in Windows for piping syntax.
      run: |
        GHC_VERSION=$(ghc --numeric-version)
        CABAL_VERSION=$(cabal --numeric-version)
        echo "GHC_VERSION=${GHC_VERSION}"     >> "${GITHUB_ENV}"
        echo "CABAL_VERSION=${CABAL_VERSION}" >> "${GITHUB_ENV}"

    - name: Configure the build
      run: |
        cabal configure --enable-tests --enable-benchmarks
        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
      with:
        path: ${{ steps.setup.outputs.cabal-store }}
        key:  ${{ runner.os }}-ghc-${{ env.GHC_VERSION }}-cabal-${{ env.CABAL_VERSION }}-plan-${{ hashFiles('**/plan.json') }}
        restore-keys: |
              ${{ runner.os }}-ghc-${{ env.GHC_VERSION }}-cabal-${{ env.CABAL_VERSION }}-

    - 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
      # Caches are immutable, trying to save with the same key would error.
      if:   ${{ !steps.cache.outputs.cache-hit || steps.cache.outputs.cache-primary-key != steps.cache.outputs.cache-matched-key }}
      uses: actions/cache/save@v3
      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