I'm trying to compile this function from Learn You a Haskell for Great Good.
removeNonUppercase st = [ c | c <- st, c `elem` ['A'..'Z']]
by placing it into a removeNonUpperCase.hs file.
It compiles fine, but when passing the argument:
ghci> removeNonUppercase "Hahaha! Ahahaha!"
the compiler says:
<interactive>:1:0: Not in scope: 'removeNonUpperCase'
Why?