I try to mimic Erlang like this: -------------------------------------------------------------------------------- {-# LANGUAGE FlexibleInstances #-} import Prelude hiding ( catch ) import Control.Monad import Control.Concurrent import Control.Exception spawn = forkIO wait = forever $ threadDelay (maxBound :: Int) receive = catch wait (!) = throwTo instance Exception String test = do let actor = receive putStrLn p <- spawn actor p ! "1" p ! "2" p ! "3" -- > test -- 1 -- <interactive>: "2" -------------------------------------------------------------------------------- but raise an exception terminates the thread. This is quite natural, of course. What I need is a messages -- something that works just like exceptions but don't stop a thread's computations. I mean, the scheduler knows about asynchronous exceptions, adding the message queue (with Chan, MVar or STM) for each process will not help in this kind of imitation. It's possible to solve this problem with the exceptions or with something? Or the message communication should be implemented as a new feature in the RTS?