track .cabal file

- closes #5

.github/workflows/consistency.yml

@@ -0,0 +1,45 @@
+---
+name: Check .cabal Consistency
+
+on: [push, pull_request]
+
+jobs:
+  check-consistency:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Save original cabal files
+        run: |
+          # shellcheck disable=SC2156
+          find . -name dist-newstyle -prune -o -type f -name '*.cabal' -exec sh -c \
+            "export i={}; grep -v '^--' \"\$i\" | grep -v '^$' > \"\$i.original\"; rm \"\$i\"" \;
+
+      - name: Set up Haskell
+        uses: haskell-actions/setup@v2
+        with:
+          enable-stack: true
+          stack-no-global: true
+
+      - name: Generate .cabal files from package.yaml
+        run: stack build --dry-run --no-install-ghc --stack-yaml=stack.yaml || true
+
+      - name: Save generated cabal file
+        run: |
+          # shellcheck disable=SC2156
+          find . -name dist-newstyle -prune -o -type f -name '*.cabal' -exec sh -c \
+            "export i={}; grep -v '^--' \"\$i\" | grep -v '^$' > \"\$i.generated\"" \;
+
+      - name: Print differences
+        run: |
+          export CORRECT=true
+          # shellcheck disable=SC2044
+          for i in $(find . -name dist-newstyle -prune -o -type f -name '*.cabal' -print); do \
+            if ! diff -u "$i.original" "$i.generated"; then \
+              CORRECT=false; \
+              continue; \
+            fi \
+          done
+          ${CORRECT}

.gitignore

@@ -1,5 +1,4 @@
 .DS_Store
-*.cabal
 .vscode/
 .stack-work/
 stack.yaml.lock