If this is meant to be under main, you need a "let": main = do let greet name = putStrLn ("Hello, " ++ name) getLine >>= greet For whatever re

If this is meant to be under main, you need a "let": main = do let greet name = putStrLn ("Hello, " ++ name) getLine >>= greet For whatever reason, I didn't learn about the magic let syntax in do-notation until relatively late. Anyways this is very elegant, but not something I could have generated early on, especially because it mixes two different sequencing syntaxes (do-notation and >>=).