Graphics program often relies on system frameworks such as GLUT or GLFW to handle window and user input. But such frameworks often impose a rigid style of callback programming, or inversion of control. It is no secret that continuation monad can deal with this issue [1]. It is also known that concurrency can be naturally expressed as continuation monads [2], and a hybrid model of event and threads [3] brings the best of both worlds. But then I'm a bit surprised to find no single library on HackageDB that can deal with this issue. Further more, I wanted something that can escape the IO monad imposed by callbacks (and FFI) and be flexible. (no, monad-control is not a solution here). So I wrote a monad-task library to handle both co-operative threads (or co-routines) and event processing in a TaskT transformer. To demonstrate its usage, I also uploaded a GLFW-task library that helps to program task monad with GLFW, which contains a sample application if you unpack its source. I documented the rationales behind this work in a (rather length but runnable literal Haskell) tutorial "Invert the Inversion of Control", and welcome any suggestions and feedbacks. monad-task: http://hackage.haskell.org/package/monad-task GLFW-task: http://hackage.haskell.org/package/GLFW-task tutorial: http://www.thev.net/PaulLiu/invert-inversion.html [1]: Quick and dirty reinversion of control, Dan Piponi. http://blog.sigfpe.com/2011/10/quick-and-dirty-reinversion-of-control.html [2]: Functional Pearls: A Poor Man's Concurrency Monad, Koen Claessen, 1999 [3]: Combining Events And Threads For Scalable Network Services. Peng Li and Steve Zdancewic. PLDI, 2007. -- Regards, Paul Liu