Hi, I send this mail to the HOpenGL mailinglist. I did not get a reply. I hope it is OK to ask this question here. I am new to Haskell, but not new to OpenGL. I am reading the tutorials on the HOpenGL page and have a few questions. - First of all, all tutorials are using GLUT. Is that really the way to go with HOpenGL? They define (among other things) a onIdle and a onDraw function. That seems to me (at least for a game) not the way to go. onIdle updates the game logic, and onDraw draws the screen. As far as I can see, it does not make sense to update the game logic more than once between consecutive calls to onDraw. Same thing is true for class to onDraw between consecutive class to onIdle. Is this accounted for in the approach? - In addition there is the onInput function. The onInput, onIdle and onDraw functions communicate (in the tutorials) using variables declared with newIORef. I come from the OO language C++ and almost no experience with functional languages. But this puzzles me. Basically they define global variables for the exchange between the callback functions, correct?!? So, for every piece of information I want to pass between these functions, I have to declare a newIORef variable? In C/C++ I find GLUT not a very good approach and prefer plain OpenGL. Does it make sense to go with plain OpenGL in Haskell too? Are there any resources on how to do that? Thanks! Nathan