Example of scripting using Haskell and Cabal

script.hs

{- cabal:
build-depends: base >= 4.11 && < 5,shelly,text
ghc-options: -Wall -O0
default-language: Haskell2010
-}

{-# LANGUAGE OverloadedStrings #-}
module Main where

import Shelly
import Data.Foldable (traverse_)
import Data.Text

-- Run `cabal run script.hs` to run script.
--
-- Run `cabal repl --build-depends=text,shelly` and then
-- `:l script.hs` to load file in REPL.

hello :: Text
hello = "Hello, world!"

main :: IO ()
main = do
  putStrLn $ unpack hello
  files <- shelly $ ls "./"
  traverse_ putStrLn files