Try build matrix

Author: lukel97

.github/workflows/haskell.yml

@@ -5,16 +5,20 @@ on: [push, pull_request]
 jobs:
  build:
 
- runs-on: ubuntu-latest
+ runs-on: ${{matrix.os}}
+ 
+ strategy:
+ matrix:
+ os: [ubuntu-latest, macOS-latest, windows-latest]
 
  steps:
  - uses: actions/checkout@v1
+ with: 
+ submodules: recursive
  - uses: actions/setup-haskell@v1
  with:
  ghc-version: '8.6.5'
  cabal-version: '3.0'
- - name: Init git submodules
- run: git submodule update --recursive --init
  - name: Install dependencies
  run: |
  cabal update