apply stylish-haskell to only module preamble+imports, if stylish-haskell fails on entire module first

haskell-reformat

#!/usr/bin/env bash

INPUT="$(cat)"
IFS=''

ERRORS="$(mktemp)"

EXIT_OK=true

if ! (echo "$INPUT" | stylish-haskell 2>>"$ERRORS") ; then
    PREAMBLE="$(echo "$INPUT" | grep -B100000 '^import')"
    LEFTOVERS="$(echo "$INPUT" | tail -n +$((1 + $(echo "$PREAMBLE" | wc -l))))"
    if echo "$PREAMBLE" | stylish-haskell 2>>"$ERRORS"; then
        echo "$LEFTOVERS"
    else
        cat "$ERRORS" 1>&2
        EXIT_OK=false
    fi
fi

rm "$ERRORS"

$EXIT_OK