gistfile1.hs

forMpar :: [a] -> (a -> IO b) -> IO [b]
forMpar xs fun = do
  sem <- newQSem (length xs)
  c <- newChan
  forM_ xs (\x -> forkIO $ wrap fun x c sem)
  waitQSem sem
  collect (length xs) c []
    where wrap f item chan qsem = f item >>= writeChan chan >> signalQSem qsem 
          collect 0 chan acc = return acc
          collect count chan acc = do !i <- readChan chan; collect (count - 1) chan i::acc



Network/BsonRPC/Util.hs:95:0:
    Occurs check: cannot construct the infinite type: b = [b]
    When generalising the type(s) for `forMpar'