Greetings, fellow haskellers. Currently I'm writing some kind of web crawler in haskell with gtk2hs gui. All network operations are run in separate thread, but sometimes input from user is needed. Afaik, gtk2hs is not thread safe, so I came up with following: I create two mvars, A and B, one for question, one for answer. Worker thread puts question in A and blocks trying to take B. Gui thread checks for question by polling with tryTakeMVar. Then question is ready, it asks user and puts his answer into B. Worker awakens and continues processing. Also, for progress report, I use a Chan which is written to by worker and is read by polling by gui thread. This scheme works, but I don't like it. All these mvars and chans create too much clutter, and polling looks rather ugly too. Is there a better way for implementing similar patterns of interaction? Best regards, Dmitry.