Paste code

 import Control.Concurrent (newMVar, putMVar, takeMVar )
 
arrIO _ =
  proc _ -> do
    counter <- newMVar 0 :: IO (MVar Int)
    takeMVar counter >>= print
    returnA -< ()
	import Control.Concurrent (newMVar, putMVar, takeMVar )

	arrIO _ =
	proc _ -> do
	counter <- newMVar 0 :: IO (MVar Int)
	takeMVar counter >>= print
	returnA -< ()