List the contents of the PATH environment variable in Haskell

lspath.hs

import System.Environment
import System.FilePath

wordsWhen :: (Char -> Bool) -> String -> [String]
wordsWhen p s = case dropWhile p s of
                  "" -> []
                  s' -> w : wordsWhen p s''
                        where (w, s'') = break p s'

main :: IO ()
main = do
  path <- getEnv "PATH"
  mapM_ putStrLn $ wordsWhen (==searchPathSeparator) path