Hello, I read your proposal. It's great but I have a few remarks : * 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. *Another problem can raise : if one render in two different OpenGL windows, he may want to use different threads for these rendering. However, this is impossible for the moment because it would implies that user threads know when a switch has occurred to a thread rendering in another context and swap OpenGL context. This implies a notion of either : allowing to execute arbitrary code on switch ; either introducing a notion of "family" of threads. When a switch occurs to a member of a family different of the last member of the family executed , some user defined code should be executed (in that case the code perform a context switch). family and members of family would be defined by user. It seems that family and OS threads are independent : it could either be multiple OS threads for a family or multiple families for an OS threads. I think a thread could be member of multiple families (even if I can't see pertinent example so far). I also think that multiple threads can be the same member of a family (multiple threads drawing in the same window). * A simple way of introducing these new notions (family, members, OS threads) would be to define them as first class value. This would ease the problem of callback : an OpenGL callback would simply be a call to an operator telling the OpenGL thread to execute really the callback. "threadsafe" could be a short hand for wrapping a callback in a call to the thread currently executing (at time of the call to threadsafe function) and give it to extern function. * To protect OpenGL operations, it would perhaps be useful to introduce a mechanism forbidding to switch between members of a family between a critical section. (I don't know what do a context switch between a glBegin and glEnd). I don't know if my proposal is pertinent but it addresses some problems that would arise. It's quite complicated but i think that there is no overcost for people who don't need using it. Best regards, Nicolas Oury