gistfile1.hs

foo :: [a] -> [[a]]
foo (x:xs) = do z <- xs
                -- nyt z :: a koska xs :: [a]
                gnng <- foo xs
                -- nyt gnng :: [a] koska foo xs :: [[a]]
                return $ [z]++gnng
                -- tämä on oikein koska [z]++gnng :: [a] ja foo:n paluutyyppi on [[a]]