Formatting configuration

.git-blame-ignore-revs

+# 2023
+########################################
+
+# Format the source with fourmolu
+10a14397e7295f79bb65ff505e52895f4864270a
+
 # 2022
 ########################################
 
@@ -33,3 +39,4 @@ b0333ec5b73ba8f7a18223b203d999b38c75281d
 
 # Move source files under 'src/'.
 52d506bb4e25489f40cb5eb594dda5595aeb93ed
+

.githooks/pre-push

+#!/usr/bin/env bash
+
+set -euxo pipefail
+
+if [[ $(uname -s) != "Linux" ]]
+then
+  PROCS=$(sysctl -n hw.logicalcpu)
+else
+  PROCS=$(nproc)
+fi
+
+if which fourmolu > /dev/null ; then
+  find Cabal Cabal-syntax cabal-install -name '*.hs' -print0 \
+    ! -path Cabal-syntax/src/Distribution/Fields/Lexer.hs \
+    ! -path Cabal-syntax/src/Distribution/SPDX/LicenseExceptionId.hs \
+    ! -path Cabal-syntax/src/Distribution/SPDX/LicenseId.hs \
+    ! -path Cabal/src/Distribution/Simple/Build/Macros/Z.hs \
+    ! -path Cabal/src/Distribution/Simple/Build/PathsModule/Z.hs \
+    | xargs -P "${PROCS}" -I {} fourmolu -q --mode check {}
+else
+  echo "Fourmolu not found, aborting."
+  exit 1
+fi

.github/PULL_REQUEST_TEMPLATE.md

@@ -2,7 +2,7 @@
 ---
 Please include the following checklist in your PR:
 
-* [ ] Patches conform to the [coding conventions](https://github.com/haskell/cabal/blob/master/CONTRIBUTING.md#conventions).
+* [ ] Patches conform to the [coding conventions](https://github.com/haskell/cabal/blob/master/CONTRIBUTING.md#other-conventions).
 * [ ] Any changes that could be relevant to users [have been recorded in the changelog](https://github.com/haskell/cabal/blob/master/CONTRIBUTING.md#changelog).
 * [ ] The documentation has been updated, if necessary.
 * [ ] Include [manual QA notes](https://github.com/haskell/cabal/blob/master/CONTRIBUTING.md#qa-notes) if your PR relates to cabal-install.

.github/workflows/linting.yml

+name: Linting
+
+on:
+  pull_request:
+  push:
+    branches: ["master"]
+
+jobs:
+  fourmolu:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v3
+    - uses: haskell-actions/run-fourmolu@v8
+      with:
+        pattern: |
+          Cabal/**/*.hs
+          Cabal-syntax/**/*.hs
+          Cabal-install/**/*.hs
+          !Cabal-syntax/src/Distribution/Fields/Lexer.hs
+          !Cabal-syntax/src/Distribution/SPDX/LicenseExceptionId.hs
+          !Cabal-syntax/src/Distribution/SPDX/LicenseId.hs
+          !Cabal/src/Distribution/Simple/Build/Macros/Z.hs
+          !Cabal/src/Distribution/Simple/Build/PathsModule/Z.hs

.github/workflows/whitespace.yml

-name: Assorted
-
-on:
-  push:
-    branches:
-      - master
-  pull_request:
-  release:
-    types:
-      - created
-jobs:
-  check:
-    name: Whitespace
-    runs-on: ubuntu-latest
-
-    env:
-     fix-whitespace-ver: '0.0.10'
-
-    steps:
-    - uses: actions/checkout@v3
-      name: Checkout sources
-
-    - name: Create directory for binary
-      run: |
-        mkdir -p $HOME/.local/bin
-
-    - uses: actions/cache@v3
-      name: Cache the binary
-      id: cache
-      with:
-        path: "~/.local/bin"
-        key: fix-whitespace-${{ env.fix-whitespace-ver }}
-
-    # See https://github.com/haskell/cabal/pull/8739
-    - name: Sudo chmod to permit ghcup to update its cache
-      run: |
-        if [[ "${{ runner.os }}" == "Linux" ]]; then
-          sudo mkdir -p /usr/local/.ghcup/cache
-          sudo chown -R $USER /usr/local/.ghcup
-          sudo chmod -R 777 /usr/local/.ghcup
-        fi
-
-    - uses: haskell/actions/setup@v2
-      if: ${{ !steps.cache.outputs.cache-hit }}
-      with:
-        ghc-version: '9.2'
-        cabal-version: latest
-
-    - name: Install fix-whitespace
-      if: ${{ !steps.cache.outputs.cache-hit }}
-      run: |
-        cabal install --ignore-project --install-method=copy --installdir=$HOME/.local/bin fix-whitespace-${{ env.fix-whitespace-ver }}
-        strip $HOME/.local/bin/fix-whitespace
-
-    - name: Check the whitespace issue
-      run: |
-        $HOME/.local/bin/fix-whitespace --check

CONTRIBUTING.md

@@ -137,38 +137,16 @@ For instance:
 Manual QA is not expected to find every possible bug, but to really challenge the assumptions of the contributor, and to verify that their own testing
 of their patch is not influenced by their setup or implicit knowledge of the system.
 
-Whitespace Conventions
-----------------------
-
-* No tab characters allowed.
-* No trailing whitespace allowed.
-* File needs to be terminated by a newline character.
-
-These conventions are enforced by the
-[fix-whitespace](https://hackage.haskell.org/package/fix-whitespace)
-tool.  Install it from hackage as usual (`cabal install fix-whitespace`)
-and run it in the project root to fix whitespace violations.
-
-The files included in the automatic whitespace check are specified in
-`fix-whitespace.yaml`.  Please add to this file if you add textfiles
-to this repository that are not included by the rules given there.
-Note that files that make essential use of tab characters (like `Makefile`)
-should _not_ be included in the automatic check.
-
-Whitespace conventions are enforced by
-[CI](https://github.com/haskell/cabal/actions/workflows/whitespace.yml).
-If you push a fix of a whitespace violation, please do so in a
-_separate commit_.
-
 
+Code Style
+---------------
 
+We use automated formatting with Fourmolu to enforce a unified style across the code bases. It is checked in the CI process.
+You can automatically format the code bases with `make style` at the top level of the project.
 
 Other Conventions
 -----------------
 
-* Try to follow style conventions of a file you are modifying, and
-  avoid gratuitous reformatting (it makes merges harder!)
-
 * Format your commit messages [in the standard way](https://chris.beams.io/posts/git-commit/#seven-rules).
 
 * A lot of Cabal does not have top-level comments.  We are trying to
@@ -227,10 +205,6 @@ Other Conventions
   #endif
   ```
 
-We like [this style guide][guide].
-
-[guide]: https://github.com/tibbe/haskell-style-guide/blob/master/haskell-style.md
-
 GitHub Ticket Conventions
 -------------------
 

Makefile

@@ -14,6 +14,19 @@ lib : $(LEXER_HS)
 exe : $(LEXER_HS)
 	$(CABALBUILD) cabal-install:exes
 
+init: ## Set up git hooks and ignored revisions
+	@git config core.hooksPath .githooks
+	## TODO
+
+style: ## Run the code styler
+	@find Cabal Cabal-syntax cabal-install -name '*.hs' \
+		! -path Cabal-syntax/src/Distribution/Fields/Lexer.hs \
+		! -path Cabal-syntax/src/Distribution/SPDX/LicenseExceptionId.hs \
+		! -path Cabal-syntax/src/Distribution/SPDX/LicenseId.hs \
+		! -path Cabal/src/Distribution/Simple/Build/Macros/Z.hs \
+		! -path Cabal/src/Distribution/Simple/Build/PathsModule/Z.hs \
+		| xargs -P $(PROCS) -I {} fourmolu -q -i {}
+
 # source generation: Lexer
 
 LEXER_HS:=Cabal-syntax/src/Distribution/Fields/Lexer.hs
@@ -227,3 +240,9 @@ users-guide-requirements: doc/requirements.txt
 doc/requirements.txt: .python-sphinx-virtualenv
 	. .python-sphinx-virtualenv/bin/activate \
 	  && make -C doc build-and-check-requirements
+
+ifeq ($(UNAME), Darwin)
+    PROCS := $(shell sysctl -n hw.logicalcpu)
+else
+    PROCS := $(shell nproc)
+endif

fourmolu.yaml

+indentation: 2
+comma-style: leading # for lists, tuples etc. - can also be 'trailing'
+import-export-style: leading
+record-brace-space: false # rec {x = 1} vs. rec{x = 1}
+indent-wheres: true # 'false' means save space by only half-indenting the 'where' keyword
+respectful: true # don't be too opinionated about newlines etc.
+haddock-style: single-line # '--' vs. '{-'
+haddock-style-module: single-line
+newlines-between-decls: 1 # number of newlines between top-level declarations
+fixities: []
+function-arrows: leading
+single-constraint-parens: never
+in-style: right-align
+let-style: auto