import Control.Monad.ST
import Data.Array.ST
import Data.Array.MArray

type Array s a = STArray s Int a

pivot :: (Int, Int) -> Array s a -> ST s Int
pivot (l,r) xs = do p <- readArray xs l
                    za

qsort :: Ord a => [a] -> [a]
qsort input = runST $ do
                xs <- makearray (1, length input) input
                getElems xs
    where makearray :: (Int, Int) -> [a] -> ST s (STArray s Int a)
          makearray = newListArray