Switch to GitHub Actions for CI

.github/workflows/build.yml

@@ -0,0 +1,30 @@
+name: build
+on: [push]
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        ghc: ['8.6.5', '8.8.4', '8.10.7', '9.0.2', '9.2.1']
+    name: Build with GHC ${{ matrix.ghc }}
+    steps:
+    - uses: actions/checkout@v2
+    - name: Setup Haskell
+      uses: haskell/actions/setup@v1
+      with:
+        ghc-version: ${{ matrix.ghc }}
+
+    - run: cp cabal.project.ci cabal.project.local
+    - run: cabal v2-update
+    - run: cabal v2-freeze
+    - uses: actions/cache@v2
+      with:
+        path: ~/.cabal/store
+        key: ${{ runner.os }}-${{ matrix.ghc }}-${{ hashFiles('cabal.project.freeze') }}
+        restore-keys: |
+          ${{ runner.os }}-${{ matrix.ghc }}-
+
+    - run: cabal v2-build
+    - run: cabal v2-test
+    - run: cabal v2-sdist

cabal.project

@@ -1,12 +1,5 @@
 packages: .
 jobs: $ncpus
 
-package *
-  haddock-html: true
-  haddock-hoogle: true
-  haddock-hyperlink-source: true
-  haddock-quickjump: true
-
 package freer-simple
   ghc-options: -j
-  haddock-options: "--optghc=-Wno-unused-imports"

cabal.project.ci

@@ -0,0 +1,5 @@
+package freer-simple
+  ghc-options: -Werror
+  documentation: true
+  benchmarks: true
+  tests: true

freer-simple.cabal

@@ -28,14 +28,14 @@ license-file: LICENSE
 homepage: https://github.com/lexi-lambda/freer-simple
 bug-reports: https://github.com/lexi-lambda/freer-simple/issues
 
-source-repository head
-  type: git
-  location: https://github.com/lexi-lambda/freer-simple
-
 extra-source-files:
   CHANGELOG.md
   README.md
 
+source-repository head
+  type: git
+  location: https://github.com/lexi-lambda/freer-simple
+
 common common
   ghc-options:
     -Wall