Question

What is wrong with this code? Trying to do a basic haskell hello world.

module Main
( hello )
where

hello :: [Char] -> [Char]
hello p = "Hello " ++ p ++ "!"

main =
  let msg = hello "World"
  putStrLn msg

Answer 1

You’re missing a do:

main = do
  let msg = hello "World"
  putStrLn msg

You’ll also want to export your main:

module Main ( main ) where

Since this is the main module, there is no need to export hello.