Re: [Haskell-beginners] forkIO and signal handlers

9 Sep 2011


      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:
...
Here's the error message. The problem is clear, not sure what to do
about it. My broken code should show my intent though.
...
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:
...
On Fri, Sep 9, 2011 at 15:35, Michael Litchard  wrote:
...
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
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