test new approach

Author: ibbem

.github/workflows/maven.yml

@@ -18,19 +18,29 @@ jobs:
     steps:
     - uses: actions/checkout@v4
     - uses: cachix/install-nix-action@v31
-    - name: Evaluate Nix expressions
+    - uses: actions/cache/restore@v4
+      id: cache
+      with:
+        path: cache-closure.nar
+        key: nix-${{ hashFiles('.github/workflows/maven.yml', 'default.nix', 'nix/**', 'pom.xml', 'local-maven-repo') }}
+        # restore-keys:
+    - name: Import cache
+      if: steps.cache.outputs.cache-hit == 'true'
+      run: |
+        nix-store --import < cache-closure.nar
+    - name: Build and export cache
+      if: steps.cache.outputs.cache-hit == 'false'
       run: |
-        nix-instantiate --expr '[ (import ./nix/github-workflow-dependencies.nix) (import ./default.nix)]' 2>&1 | grep '^/nix/store/' | tee derivations
-        echo 'dry build'
-        nix-store --realize --dry-run $(< derivations) 2>&1 | tee dry-build
-        echo 'to be fetched'
-        sed '1,/^these .* will be fetched/ d; s/^  //' dry-build | tee fetch
-        echo 'to be built'
-        sed -n '2,/^these .* will be fetched/ p' dry-build | grep -v '^these' | sed 's/  //' | tee built
-    - name: Fetch
-      run: nix-store --realize $(< fetch)
+        nix-build --out-link dependencies nix/github-workflow-dependencies.nix
+        nix-store --export $(nix-store --query --requisites dependencies) > cache-closure.nar
+    - uses: actions/cache/save@v4
+      if: steps.cache.outputs.cache-hit == 'false'
+      with:
+        path: cache-closure.nar
+        key: nix-${{ hashFiles('.github/workflows/maven.yml', 'default.nix', 'nix/**', 'pom.xml', 'local-maven-repo') }}
+        # restore-keys:
     - name: Build
-      run: nix-store --realize $(< built)
+      run: nix-build
     - name: Upload Javadoc artifact
       if: ${{ github.event_name == 'push' && github.event.ref == 'refs/heads/main' }}
       uses: actions/upload-pages-artifact@v3