#!/usr/bin/env stack {- stack script --resolver lts-11.6 --install-ghc --package protolude --package optparse-generic -} {-# LANGUAGE NoImplicitPrelude #-} {-# LANGUAGE OverloadedStrings #-} import Protolude import System.Environment (getArgs) main :: IO () main = do arguments <- getArgs case head arguments of Just filename -> die ("The first argument is: " <> toS filename) Nothing -> die "Please enter a filename"