Nicolas Oury
* I think that, if it is not too much complicated, it could be great to put many threads in the OpenGL OS thread. The goal of concurrent Haskell was to allow concurrency for expressivity. It would be a pity to lose this in part of programs for technical reason. Having this possibility would also be a pro this language : Haskell would be the only language to have safe multithreaded OpenGL programming.
Note that you can achieve the goal of having multithreaded OpenGL programming using Wolfgang's proposal. All you need to do is fork a worker thread which will make all the OpenGL calls. Any green thread wanting to make a call just sends a request to the worker and waits for a response. The code would look something like this: type Response = () type Job = IO Response type Ch = (MVar Job, MVar Response) -- the worker thread runs this worker :: Ch -> IO () worker ch@(jobs, responses) = do j <- readMVar jobs a <- j writeMVar responses a worker ch -- green threads call this to get work done doit :: Ch -> Job -> IO Response doit (jobs, responses) j = do writeMVar jobs j readMVar response Things get a little tedious if you want multiple return types. -- Alastair Reid alastair@reid-consulting-uk.ltd.uk Reid Consulting (UK) Limited http://www.reid-consulting-uk.ltd.uk/alastair/