Hi Alexander, I went looking for something to clean up rss2irc's thread management, and your recently released thespian package looks like the simplest, most practical actors/erlang/OTP-ish lib for haskell so far. Thanks! I need to restart threads (actors) in a controlled way when they die or hang. I think some of all of that is also part of Erlang/OTP, and maybe it's already on your todo list. Here are some notes I made, for your interest and in case you have any further thoughts. I thought of adding some actor-transforming combinators like these: -- | Spawn the specified action and restart it whenever it dies, unless -- the restart frequency exceeds any of the given maximum frequencies in -- which case throw an exception. restart :: [Frequency] -> IO a -> IO Address restart fs action = spawn $ do setFlag TrapRemoteExceptions let start times = [] forever t <- getCurrentTime update start times when (any fs exceeded by start times) throw error worker <- spawn action monitor worker receive worker [Case _ -> return ()] -- | Convert hangs to exceptions using a watchdog timer: spawn the -- specified action under the control of a watcher which monitors it and -- also kills it and throws an exception if the worker ever fails to -- send (something) to the watcher within the specified interval. watchdog :: Seconds -> (Address -> IO a) -> IO Address watchdog t action = spawn $ do watcher <- self worker <- spawn $ action watcher monitor worker forever receiveTimeout t [Case _ -> return () Default -> throw error ] which I would use something like: main = do (feed, bot) <- ... spawn $ do reader <- restart [MaxPerHour 2] $ watchdog 60 $ feedReader feed bot announcer <- restart [MaxPerHour 2] $ watchdog 60 $ ircAnnouncer bot responder <- restart [MaxPerHour 2] $ watchdog 60 $ ircResponder bot monitor reader monitor announcer monitor responder setFlag TrapRemoteExceptions receive [Case e :: RemoteException -> exitFailure (show e) -- one of the above died or hung too frequently ] but the types aren't right. I'm not sure if these combinators are possible with the current thespian api. Also they would complicate things, eg what is the address of a restarted actor ? On second thoughts it might be better if these features were built in to the library. I imagine something like: main = do ... reader <- spawnWith [RestartSpec [MinInterval (minutes 5), MaxPerHour 3, MaxPerWeek 6], Watchdog (seconds 60)] $ feedReader feed bot feedReader = do forever poll feed, do stuff resetWatchdog What do you think ? Best - Simon