CI: GitHub: Cabal: improvement of the GitHub caching

A riff on the theme of
https://markkarpov.com/post/github-actions-for-haskell-ci.html

.github/workflows/Cabal-Linux.yml

@@ -8,6 +8,8 @@ on:
   schedule:
     - cron: "45 02 * * *"
 
+env:
+  cabalConfig: --enable-tests --enable-benchmarks --disable-optimization --enable-deterministic
 
 jobs:
 
@@ -18,18 +20,13 @@ jobs:
       matrix:
         ghc: [ "8.10", "8.4" ]
     steps:
-      - uses: actions/checkout@v2
+      - name: "Git checkout"
+        uses: actions/checkout@v2
         with:
           submodules: recursive
-      - name: "Cache of ~/.cabal/packages, ~/.cabal/store and dist-newstyle"
-        uses: actions/cache@v2
-        with:
-          path: |
-            ~/.cabal/packages
-            ~/.cabal/store
-            dist-newstyle
-          key: ${{ runner.os }}-Cabal-${{ matrix.ghc }}
-      - uses: haskell/actions/setup@v1
+      - name: "Haskell env setup"
+        id: HaskEnvSetup
+        uses: haskell/actions/setup@v1
         with:
           ghc-version: ${{ matrix.ghc }}
       - name: "Install additional system packages"
@@ -37,6 +34,20 @@ jobs:
       #  2020-08-01: NOTE: Nix instantiate still needed for HNix tests
       - name: "Install Nix"
         uses: cachix/install-nix-action@v12
-      - run: cabal v2-configure --disable-optimization --enable-tests --enable-deterministic
-      - run: cabal v2-build
-      - run: cabal v2-test
+      - name: "Repository update"
+        run: cabal v2-update
+      # NOTE: Freeze is for the caching
+      - name: "Configuration freeze"
+        run: cabal v2-freeze $cabalConfig
+      - name: "Configuring GitHub cache"
+        uses: actions/cache@v2
+        with:
+          path: |
+            ${{ steps.HaskEnvSetup.outputs.cabal-store }}
+            dist-newstyle
+          key: ${{ runner.os }}-Cabal-${{ matrix.ghc }}-${{ hashFiles('cabal.project.freeze') }}
+          restore-keys: ${{ runner.os }}-Cabal-${{ matrix.ghc }}-
+      - name: "Build"
+        run: cabal v2-build $cabalConfig
+      - name: "Tests"
+        run: cabal v2-test $cabalConfig

.github/workflows/On-Release-Cabal-Linux.yml

@@ -5,6 +5,9 @@ on:
     # created: a draft is saved, or a release or pre-release is published without previously being saved as a draft
     types: [ created ]
 
+env:
+  cabalConfig: --enable-tests --enable-benchmarks --disable-optimization --enable-deterministic
+
 jobs:
 
   build10:
@@ -15,18 +18,13 @@ jobs:
         # Since CI by default tests boundary GHCs, test middle versions of GHCs
         ghc: [ "8.8", "8.6"]
     steps:
-      - uses: actions/checkout@v2
+      - name: "Git checkout"
+        uses: actions/checkout@v2
         with:
           submodules: recursive
-      - name: Cache of ~/.cabal/packages, ~/.cabal/store and dist-newstyle
-        uses: actions/cache@v2
-        with:
-          path: |
-            ~/.cabal/packages
-            ~/.cabal/store
-            dist-newstyle
-          key: ${{ runner.os }}-Cabal-${{ matrix.ghc }}
-      - uses: haskell/actions/setup@v1
+      - name: "Haskell env setup"
+        id: HaskEnvSetup
+        uses: haskell/actions/setup@v1
         with:
           ghc-version: ${{ matrix.ghc }}
       - name: "Install additional system packages"
@@ -34,6 +32,20 @@ jobs:
       #  2020-08-01: NOTE: Nix instantiate still needed for HNix tests
       - name: "Install Nix"
         uses: cachix/install-nix-action@v12
-      - run: cabal v2-configure --disable-optimization --enable-tests --enable-deterministic
-      - run: cabal v2-build
-      - run: cabal v2-test
+      - name: "Repository update"
+        run: cabal v2-update
+      # NOTE: Freeze is for the caching
+      - name: "Configuration freeze"
+        run: cabal v2-freeze $cabalConfig
+      - name: "Configuring GitHub cache"
+        uses: actions/cache@v2
+        with:
+          path: |
+            ${{ steps.HaskEnvSetup.outputs.cabal-store }}
+            dist-newstyle
+          key: ${{ runner.os }}-Cabal-${{ matrix.ghc }}-${{ hashFiles('cabal.project.freeze') }}
+          restore-keys: ${{ runner.os }}-Cabal-${{ matrix.ghc }}-
+      - name: "Build"
+        run: cabal v2-build $cabalConfig
+      - name: "Tests"
+        run: cabal v2-test $cabalConfig