ci(#348): add fourmolu auto-commit to CI

.github/workflows/haskell.yml

@@ -118,6 +118,22 @@ jobs:
           ${{ runner.os }}-build-${{ env.cache-name }}-
           ${{ runner.os }}-build-
           ${{ runner.os }}-
+
+    - name: Install fourmolu
+      run: cabal install fourmolu --overwrite-policy=always
+
+    - name: Lint Haskell
+      run: |
+        find . -name '*.hs' -exec sh -c 'for file do fourmolu -i "$file"; done' sh {} +
+
+    - name: Auto-commit lint
+      uses: stefanzweifel/git-auto-commit-action@v4
+      with:
+        commit_message: fourmolu auto-commit
+        commit_user_name: GitHub Action
+        commit_user_email: [email protected]
+        branch: ${{ github.head_ref }}
+
     - name: Install LIBSODIUM
       run: |
         git clone https://github.com/input-output-hk/libsodium

fourmolu.yaml

@@ -1,7 +1,47 @@
+# Number of spaces per indentation step
 indentation: 2
-comma-style: leading
+
+# Max line length for automatic line breaking
+column-limit: none
+
+# Styling of arrows in type signatures (choices: trailing, leading, or leading-args)
+function-arrows: leading
+
+# How to place commas in multi-line lists, records, etc. (choices: leading or trailing)
+comma-style: trailing
+
+# Styling of import/export lists (choices: leading, trailing, or diff-friendly)
+import-export-style: diff-friendly
+
+# Whether to full-indent or half-indent 'where' bindings past the preceding body
+indent-wheres: false
+
+# Whether to leave a space before an opening record brace
 record-brace-space: true
-indent-wheres: true
-respectful: true
-haddock-style: multi-line
+
+# Number of spaces between top-level declarations
 newlines-between-decls: 1
+
+# How to print Haddock comments (choices: single-line, multi-line, or multi-line-compact)
+haddock-style: multi-line
+
+# How to print module docstring
+haddock-style-module: null
+
+# Styling of let blocks (choices: auto, inline, newline, or mixed)
+let-style: auto
+
+# How to align the 'in' keyword with respect to the 'let' keyword (choices: left-align, right-align, or no-space)
+in-style: right-align
+
+# Whether to put parentheses around a single constraint (choices: auto, always, or never)
+single-constraint-parens: never
+
+# Output Unicode syntax (choices: detect, always, or never)
+unicode: always
+
+# Give the programmer more choice on where to insert blank lines
+respectful: false
+
+# Fixity information for operators
+fixities: []