Hi all, I have a program which implements Conway's Game Of Life. It even has an open GL UI which shockingly works. I've followed a tutorial (http://blog.mikael.johanssons.org/archive/2006/09/opengl-programming-in-hask...) which tells how to get the open GL to animate, and according to my sysouts, that's working to. The problem I have comes with the fact that between every frame I want to evolve my world but I'm really struggling working out how to get the state stuff working. Here's a snippet of my main function; main = do world <- sequence (take (worldSize * worldSize) $ repeat rand) -- randomly generate a square world -- code snipped out displayCallback $= (display position world) -- display method which is called on every frame redraw mainLoop Here, world is a [Int] and represents my cells. The display function as referenced by "displayCallback" is the function that is called back to everytime the frame is redrawn. I also have another function which takes in a world, updates the state of the cells and the evolved world, thus; evolve :: [Int] -> [Int] I've been reading through (a lot of) tutorials on the state monad but I'm not any closer to working out how I make the call to display take some kind of updated world. I've also got the following code; type World = State [Int] evolveS :: World [Int] evolveS = do w <- get let w2 = evolve w put w2 return w2 Which I believe to be the correct code for wrapping my [Int] in the state monad but now I have two problems; 1) I don't know if it's correct 2) I don't know how to apply it, even if it is Can anyone offer any advice? Many thanks, Tom