stats :: String -> String
    stats =
        unwords .
        sequence [show . length . words,
                  show . length . lines,
                  show . length]

This improves the statistics code slightly, but uses some monadic
machinery you may not be familiar with.  Another way to read the 'stats'
function is this:

    stats :: String -> String
    stats str =
        unwords [show . length . words $ str,
                 show . length . lines $ str,
                 show . length $ str]