Beispiel (ohne STM)

main = do
  let steps = 10000
      threads = GHC.Conc.numCapabilities
  counter <- newIORef 0
  ch <- newChan -- als Latch benutzt
  forM [ 1 ..  threads ] $ \ t -> forkIO $ do
      forM [ 1 .. steps ] $ \ s -> do
          c <- readIORef counter
          writeIORef counter (c + 1)
      writeChan ch ()
  forM [ 1 .. threads ] $ \ s -> readChan ch
  c <- readIORef counter 
  putStrLn $ show c