Update the CI config.

.github/workflows/haskell.yml

@@ -12,25 +12,41 @@ jobs:
         cabal: ["latest"]
 
     steps:
-    - uses: actions/checkout@master
-      if: github.event.action == 'opened' || github.event.action == 'synchronize'
+    - uses: actions/checkout@v2
+      if: github.event.action == 'opened' || github.event.action == 'synchronize' || github.event.ref == 'refs/heads/master'
 
-    - uses: actions/setup-haskell@v1
+    - uses: actions/setup-haskell@v1.1.2
       name: Setup Haskell
       with:
         ghc-version: ${{ matrix.ghc }}
         cabal-version: ${{ matrix.cabal }}
 
+    - uses: actions/cache@v1
+      name: Cache ~/.cabal/packages
+      with:
+        path: ~/.cabal/packages
+        key: ${{ runner.os }}-${{ matrix.ghc }}-cabal-packages
+    - uses: actions/cache@v1
+      name: Cache ~/.cabal/store
+      with:
+        path: ~/.cabal/store
+        key: ${{ runner.os }}-${{ matrix.ghc }}-cabal-store
+    - uses: actions/cache@v1
+      name: Cache dist-newstyle
+      with:
+        path: dist-newstyle
+        key: ${{ runner.os }}-${{ matrix.ghc }}-fused-effects-exceptions-dist
+
     - name: Install dependencies
       run: |
         cabal v2-update
-        cabal v2-configure --enable-tests --write-ghc-environment-files=always -j2
-        cabal v2-build --only-dependencies
+        cabal v2-configure --project-file=cabal.project.ci --enable-tests --write-ghc-environment-files=always -j2
+        cabal v2-build     --project-file=cabal.project.ci --only-dependencies all
 
     - name: Build & test
       run: |
-        cabal v2-build
-        cabal v2-test
-        cabal v2-haddock
-        cabal v2-sdist
+        cabal v2-build   --project-file=cabal.project.ci
+        cabal v2-run     --project-file=cabal.project.ci test
+        cabal v2-haddock --project-file=cabal.project.ci
+        cabal v2-sdist   --project-file=cabal.project.ci
         cabal check