{-# OPTIONS_GHC -cpp -fglasgow-exts #-}
import Data.Array.IO
import Data.Array.Base
import Control.Concurrent.Locking

type WithLocking1 (a :: * -> * -> *) e m = WithLocking (a e m)
type WithLocking2 (a :: * -> * -> *) = WithLocking1 a

instance (MArray (a :: * -> * -> *) e m) => (MArray (WithLocking2 a) e m) where
    newArray lu e = newArray lu e >>= addLocking
    newArray_ lu  = newArray_ lu  >>= addLocking
    unsafeRead = liftLock2 unsafeRead
    unsafeWrite = liftLock3 unsafeWrite

main = do arr <- newArray (0,9) 0 >>= addLocking
          readArray arr 0 >>= writeArray arr 1