[Haskell-beginners] IO - getContents - putStrLn

[Robert Heumüller]

Hi,

this is probably an easy question, but i simply can't figure out, why
this does not work:

import Data.Char

main = do
    contents <- getContents
    putStrLn $ show $ splitcomma contents

splitcomma = split ','

split :: Char -> String -> [String]
split _ "" = [""]
split sp (c:cs)
    | c == sp = "": rest
    | otherwise = (c : head rest) : tail rest
    where
       rest = split sp cs

The program compiles and runs without any problems. But there is
absolutely no output, when f.eg. i type "hello, world" and hit return.
Why would that be?

Thank you very much