import           Data.List     (unfoldr)
import           System.Random

headTail (x:xs) = (x, xs)

bubbleSort :: Ord a => [a] -> [a]
bubbleSort = unfoldr (fmap headTail . sort) where
    sort []     = Nothing
    sort (x:xs) = Just $ foldl f [x] xs
    f (z:zs) y  | z < y     = z : y : zs
                | otherwise = y : z : zs

main :: IO ()
main = do
  xs <- randomRs ('a', 'z') `fmap` getStdGen
  print $ bubbleSort $ take 42 xs