add: github actions

.github/workflows/haskell.yml

@@ -0,0 +1,45 @@
+name: CI
+
+on:
+  push:
+    branches: [ "mistress" ]
+
+jobs:
+
+  stack:
+    name: stack / ghc ${{ matrix.ghc }}
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        os: [ubuntu-latest, macOS-latest, windows-latest]
+        cabal: ["3.6.2.0"]
+        ghc:
+          - "9.4.7"
+
+    steps:
+    - uses: actions/checkout@v2
+
+    - uses: haskell/actions/[email protected]
+      name: Setup Haskell Stack
+      with:
+        ghc-version: ${{ matrix.ghc }}
+        stack-version: ${{ matrix.stack }}
+
+    - uses: actions/cache@v2
+      name: Cache ~/.stack
+      with:
+        path: ~/.stack
+        key: ${{ runner.os }}-${{ matrix.ghc }}-stack
+
+    - name: Install dependencies
+      run: |
+        stack build --system-ghc --test --bench --no-run-tests --no-run-benchmarks --only-dependencies
+
+    - name: Build
+      run: |
+        stack build --system-ghc --test --bench --no-run-tests --no-run-benchmarks
+
+    - name: Test
+      run: |
+        stack test --system-ghc
+