Add fourmolu as formatter

Author: rowanG077

.github/workflows/ci.yml

@@ -13,6 +13,18 @@ concurrency:
   cancel-in-progress: true
 
 jobs:
+  fourmolu:
+    runs-on: ubuntu-latest
+    steps:
+      # Note that you must checkout your code before running haskell-actions/run-fourmolu
+      - uses: actions/checkout@v3
+      - uses: haskell-actions/run-fourmolu@v9
+        with:
+          version: "0.14.0.0"
+          pattern: |
+            *.hs
+            !src/Protocols/Cpp.hs
+
   build_mac_windows:
     name: Build and run limited tests
     runs-on: ${{ matrix.os }}

format.sh

@@ -0,0 +1,64 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+# Help message
+show_help() {
+    local script_name
+    script_name=$(basename "$0")
+    echo "Fourmolu formatting Script.
+
+Usage:
+  $script_name diff    Format the current git diff.
+  $script_name full    Format all source files.
+  $script_name check   Check the formatting of the source files.
+  $script_name (-h | --help)
+
+Options:
+  -h --help     Show this screen."
+}
+
+# Main script logic
+if [[ "$#" -eq 0 || "$1" == "-h" || "$1" == "--help" ]]; then
+    show_help
+    exit 0
+fi
+
+exclude_files=(
+  "src/Protocols/Cpp.hs"
+)
+
+ghc_opts=(
+  "-XTemplateHaskell"
+)
+
+ghc_opt_flag=""
+for opt in "${ghc_opts[@]}"; do
+  ghc_opt_flag+="-o ${opt} "
+done
+
+# Make sure it doesn't matter from where this script is executed
+DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
+cd $DIR
+
+if [ $1 == "diff" ] ; then
+  src_files=$(git diff --cached --name-only --diff-filter=ACMR -- '*.hs')
+else
+  src_files=$(find . -type f -name "*.hs")
+fi
+
+src_files_str=$(printf "%s\n" "${src_files[@]}" | sed 's| |\\ |g')
+exclude_files_str=$(printf "%s\n" "${exclude_files[@]}" | sed 's| |\\ |g')
+src_files=$(echo "$src_files_str" | grep -vwE  "$exclude_files_str")
+
+if [ -z "$src_files" ]; then
+  exit 0;
+fi
+
+if [[ "$1" == "diff" || "$1" == "full" ]] ; then
+  fourmolu --mode inplace $src_files
+elif [[ "$1" == "check" ]] ; then
+  fourmolu $ghc_opt_flag --mode check $src_files
+else
+  echo "Expected a single argument, \"full\", \"diff\", \"check\" or \"--help\"" >&2
+  exit 3
+fi

fourmolu.yaml

@@ -0,0 +1,3 @@
+indentation: 2
+column-limit: 90
+