Stack launcher that doesn't rebuild the world upon a sneeze of flags

stack.sh

#!/usr/bin/env bash

tests=false
benches=false
fast=false
for arg in "$@"; do
    case "$arg" in
        --test|test) tests=true ;;
        --bench|bench) benches=true ;;
        --fast) fast=true ;;
    esac
done

workdir=".stack-work"
( $tests || $benches || $fast ) && workdir+="/target"
$tests && workdir+="-test"
$benches && workdir+="-bench"
$fast && workdir+="-fast"
stack --work-dir="$workdir" "$@"