Hello All I have two questions. 1. I wrote this code to create 10 simultaneous threads. Could some one please tell me if this is correct or not ? incr_count :: MVar () -> MVar Int -> IO () incr_count m n = ( forM_ [ 1..10000 ] $ \_ -> modifyMVar_ n ( return . ( + 10 ) ) ) >> putMVar m () main :: IO() main = do count <- newMVar 0 list <- forM [1..10] $ \_ -> newEmptyMVar forM_ list $ \var -> forkIO . incr_count var $ count forM_ list $ \var -> takeMVar var val <- takeMVar count print val 2. I am trying to create race condition which makes the variable in inconsistent state. Could some one please tell me how to achieve this ? I look at IORef but it does not have function like modifyMVar_. Mukesh Tiwari