freeCodeCamp/guide/english/haskell/hello-world/index.md

title
Hello World Program

The simplest Hello World Program in Haskell

main :: IO ()
main = do
    putStrLn "Hello World"

Hello World using function composition

hello :: String
hello = "Hello World"

printer :: String -> IO ()
printer = putStrLn . show 

main :: IO ()
main = printer hello