[hoc-users] Re: HOC and threads (was: performSelectorWithObject problems)

[Wolfgang T. <wol...@gm...>]

Christian Hofer wrote:

> By the way, is there a way to get MVar concurrency working together  
> with HOC? Can I use MVars just like that (after telling Cocoa to  
> run thread-safe)? Do I have to use POSIX threads?

Compile your program using the -threaded option to ghc in order to  
enable the threaded run time system.
Then,

"forkIO" spawns an "unbound" (lightweight) thread. The RTS may run  
multiple lightweight threads in a single POSIX thread. Do not call  
Cocoa from threads created by forkIO.

"forkOS" spawns a POSIX thread.

Best of all, you can also use NSThread from HOC.

And YES, MVars will work between all those different threads.

Note that if you don't use -threaded, calls to forkIO will cause a  
run time error and calls to any Haskell code from other OS threads  
(NSThreads, pthreads, whatever) will most likely result in a crash.

Cheers,

Wolfgang