hwp-book/code/cmdline_1.hs

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2018-06-20 20:11:04 +00:00
#!/usr/bin/env stack
-- stack --resolver lts-11.6 script
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE NoImplicitPrelude #-}
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"