Re: [Haskell-beginners] forkIO and signal handlers

Handler is not IO (), it is a handler. Try this: installHandler userDefinedSignal1 (Catch (forkIO (worldHandler world jCount) >> return ())) Nothing On Fri, Sep 9, 2011 at 3:54 PM, Michael Litchard wrote:

forgot to paste in the error message, oops

copy_take.lhs:48:51:    Couldn't match expected type `IO ()' with actual type `Handler'    In the second argument of `($)', namely      `Catch $ worldHandler world jCount'    In the second argument of `installHandler', namely      `(forkIO $ Catch $ worldHandler world jCount)'    In a stmt of a 'do' expression:        installHandler          userDefinedSignal1          (forkIO $ Catch $ worldHandler world jCount)          Nothing Failed, modules loaded:

On Fri, Sep 9, 2011 at 12:53 PM, Michael Litchard wrote:

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Here's the error message. The problem is clear, not sure what to do about it. My broken code should show my intent though.

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main :: IO () main = do     let world = (newEmptyTMVar :: ProcessState)     let jCount = (newEmptyTMVar :: JobCount)     installHandler userDefinedSignal1 (forkIO $ Catch $ worldHandler world jCount) Nothing     sequence_ $ repeat $ worldCheck

I'd like to fork in Main. Right now I'm forking in worldHandler. If that's what I have to do, then I'll just move on. But I'd like to keep the forkIO call in Main if possible.

On Fri, Sep 9, 2011 at 12:46 PM, Brandon Allbery wrote:

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On Fri, Sep 9, 2011 at 15:35, Michael Litchard wrote:

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Thanks for the reply. The problem isn't signal handling, nor is it using forkIO. It's using both of them together.

I think you'll have to provide an example of what you're trying to do and the error message you get. -- brandon s allbery                                      allbery.b@gmail.com wandering unix systems administrator (available)     (412) 475-9364 vm/sms

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