update CI

Author: sheaf

.github/workflows/ci.yml

@@ -14,26 +14,58 @@ jobs:
       matrix:
         ghc:
           - "latest"
+          - "9.12.2"
           - "9.10.1"
-          - "9.8.2"
-          - "9.6.2"
-          - "9.4.7"
-          - "9.2.5"
+          - "9.8.4"
+          - "9.6.7"
+          - "9.4.8"
+          - "9.2.8"
           - "9.0.2"
 
     steps:
-    - name: Checkout commit
-      uses: actions/checkout@v3
-      if: github.event.action == 'opened' || github.event.action == 'synchronize' || github.event.ref == 'refs/heads/main'
+    - uses: actions/checkout@v4
 
-    - name: Set up GHC & cabal
-      uses: haskell/actions/setup@v2
+    - name: Set up GHC ${{ matrix.ghc }}
+      uses: haskell-actions/setup@v2
+      id: setup
       with:
         ghc-version: ${{ matrix.ghc }}
-        cabal-version: "latest"
+        # Defaults, added for clarity:
+        cabal-version: 'latest'
+        cabal-update: true
 
-    - name: Build
-      run: cabal build
+    - name: Configure the build
+      run: |
+        cabal configure --disable-documentation
+        cabal build all --dry-run
+      # The last step generates dist-newstyle/cache/plan.json for the cache key.
 
-    - name: Test
-      run: cabal test
+    - name: Restore cached dependencies
+      uses: actions/cache/restore@v4
+      id: cache
+      env:
+        key: ${{ runner.os }}-ghc-${{ steps.setup.outputs.ghc-version }}-cabal-${{ steps.setup.outputs.cabal-version }}
+      with:
+        path: ${{ steps.setup.outputs.cabal-store }}
+        key: ${{ env.key }}-plan-${{ hashFiles('**/plan.json') }}
+        restore-keys: ${{ env.key }}-
+
+    - name: Install dependencies
+      # If we had an exact cache hit, the dependencies will be up to date.
+      if: steps.cache.outputs.cache-hit != 'true'
+      run: cabal build all --only-dependencies
+
+    # Cache dependencies already here, so that we do not have to rebuild them should the subsequent steps fail.
+    - name: Save cached dependencies
+      uses: actions/cache/save@v4
+      # If we had an exact cache hit, trying to save the cache would error because of key clash.
+      if: steps.cache.outputs.cache-hit != 'true'
+      with:
+        path: ${{ steps.setup.outputs.cabal-store }}
+        key: ${{ steps.cache.outputs.cache-primary-key }}
+
+    - name: Build if-instance
+      run: cabal build if-instance
+
+    - name: Test if-instance
+      run: cabal test if-instance