Api.hs

orderedForkIO :: [IO a] -> IO [a]
orderedForkIO actions = do
  -- create a blocking container to hold the results for each IO action
  mvars <- replicateM (length actions) newEmptyMVar
  -- fork and run the action then put the result in the container
  let run mvar action = forkIO $ action >>= putMVar mvar
  -- fork and run each action with a container in the local run function
  forkIO $ zipWithM_ run mvars actions
  -- collect all the results, blocking until they are finished
  mapM takeMVar mvars