[Haskell-cafe] GUI Program Hangs in GHCI

[Jason Dagit]

On Sun, Jul 3, 2011 at 8:31 PM, Alexander Solla <alex.solla at gmail.com> wrote:
>
>
> On Sun, Jul 3, 2011 at 5:16 PM, Jason Dagit <dagitj at gmail.com> wrote:
>>
>> Hello,
>>
>> I have a GUI program that when I compile it and run it there are no
>> problems.  When I load it into GHCI and type, "main", it loads the
>> main window but there are no window decorations and the program hangs
>> to the point where I have to kill the ghci process.  You see a
>> spinning cursor when you mouse over the window.
>
> I don't know if this is the same issue, but it sounds like it at first
> glance:
> http://www.haskell.org/pipermail/haskell-cafe/2011-May/092029.html

Heh.  Yes, good memory!  That's a link to an email I wrote in response
to Conal.  I'm looking into the issues that Conal mentions there.

So far I've discovered that there is a bug in the Objective-C part of
glfw when it inits threads[1].  Fixing that bug makes it so that I can
use forkIO in the compiled version of my program but I still have the
bad behavior in ghci.  I think the remaining bit is that OSX (and
probably windows too) makes it very hard to run your event loop on a
thread other than your original thread[2].  I'm now wondering if the
threading model in GHC even gives me enough control to handle this
situation correctly.

Jason

[1] https://sourceforge.net/tracker/?func=detail&aid=3352963&group_id=72569&atid=534938
[2] http://www.cocoabuilder.com/archive/cocoa/205803-event-loop-in-secondary-thread-nibless-cocoa.html