niv/script/fmt

#!/usr/bin/env bash
###
### fmt - Format Haskell files with Ormolu
###
### Usage:
###   fmt [-c|--check]
###
### Options:
###   -c,--check        Only check formatting, don't change files

set -euo pipefail

help() {
    sed -rn 's/^### ?//;T;p' "$0"
}

fmt() {
    local mode="$1"
    command -v ormolu >/dev/null 2>&1 || {
        echo >&2 "error: ormolu not found. run this in niv's nix-shell"
        exit 1
    }

    needs_formatting=( )
    for f in $(find . -name '*.hs')
    do
        echo "checking: $f"
        if ! ormolu --mode "$mode" "$f"; then
            needs_formatting+=( "$f" )
        fi
    done

    if [ ${#needs_formatting[@]} -eq 0 ]; then
        echo All files checked for formatting
    else
        echo The following files need formatting:
        for i in "${needs_formatting[@]}"; do
            echo " - $f"
        done
        if [ "$mode" == "check" ]; then
            exit 1
        fi
    fi
}

if [ "$#" == "0" ]; then
    fmt "inplace"
elif [ "$1" == "-c" ] || [ "$1" == "--check" ]; then
    fmt "check"
elif [ "$1" == "-h" ] || [ "$1" == "--help" ]; then
    help
    exit 0
else
    help
    exit 1
fi