Get Supported GHC Version

• Get Supported GHC Version
  • Inputs
  • Outputs
  • Example Usage

This GitHub Action automatically detects the latest GHC (Glasgow Haskell Compiler) version compatible with your Haskell project's base dependency constraint in package.yaml.

Useful for CI/CD workflows where you want to install a GHC version that satisfies your project's dependency bounds.

Inputs

Input	Description	Default	Required
package-yaml-path	Path to your package.yaml file relative to the repo root	package.yaml	No
validate-lower-bound	Fail if the base lower bound covers GHC major versions with breaking changes below the minimum version in tested-with in your package.yaml	false	No

Outputs

Output	Description
max-ghc-version	The latest compatible GHC version to install
min-ghc-version	The oldest GHC version whose base satisfies the lower bound
ghc-version	Deprecated - use max-ghc-version instead

Example Usage

name: CI

on: [push, pull_request]

jobs:
  setup:
    runs-on: ubuntu-latest

    steps:
      - name: Checkout code
        uses: actions/checkout@v4
      - name: Get supported GHC versions
        id: get-ghc
        uses: webdevred/get-supported-ghc@v0.0.1
        with:
          package-yaml-path: examples/package.yaml
          validate-lower-bound: true
      - name: Set up GHC and Cabal
        uses: haskell-actions/setup@v2.8.0
        with:
          ghc-version: "${{ steps.get-ghc.outputs.max-ghc-version }}"

For validate-lower-bound to work, add a tested-with field to your package.yaml:

tested-with: GHC == 9.6.4, GHC == 9.8.2, GHC == 9.10.1
dependencies:
  - base >= 4.18 && < 4.22

If the base lower bound covers GHC major versions below your tested minimum (e.g. lower bound allows GHC 8.x but you only test with GHC 9.x), the action fails with a descriptive error.