On Mon, 2006-11-13 at 17:10 +0300, Bulat Ziganshin wrote:
The one thing you should be aware of is that Windows + Threading + Gtk2Hs + Gtk + GHC = Pain.
why? are you tried to call Gtk2Hs from only one thread?
I think so, yes. Or there are bizare -threaded restrictions. Only Duncan (and perhaps Simon Marlow) understand this. I merely got bit by it...
it will be great to see comments about this. it's impossible to write my program without using threaded RTS
This is a problem for all GUI libs, it's not something that's different between Gtk2Hs and wxHaskell. I think the problem is better understood in Gtk2Hs because we have tried to tackle it. I've written some multi-threaded GUI apps when using the single-threaded RTS. I have no idea if you can use threads with wxHaskell, you'd have to ask someone who knows more about it. As for the threaded RTS, currently that's only ok if you never make GUI calls from more than one Haskell thread. The reason for the restriction is that GUI libs like wxWiddgets and Gtk+ are really designed to be used in a single threaded manner[1]. I know Gtk+ does have some support for using multiple threads but it requires a lot of explicit locking so it's not easy to use from Haskell where we expect to be able to use light weight threads with ease. The problem at the moment with GUIs and GHC's threaded RTS is that there is now way to specify that all the Haskell threads that want to do GUI stuff must run on a single OS thread. It's not impossible to solve but it requires either more support from the RTS or it needs a totally different approach, perhaps using a Haskell-level threading GUI monad rather than the IO monad. Duncan [1] in fact on windows it's even worse, not only must there be no concurrent modification of GUI objects but the windows GDI enforces that *only* the thread that created an object may access/modify that object. That's a pretty severe restriction which is why we would normally say that the GUI is just single threaded rather than going into the nasty details of how exactly you really do GUIs with multiple OS threads. It's so hard to do that it's effectively just single threaded.