Oh, in case the code would be helpful.. ;) import Data.Set (toList, fromList, intersection, size) import Data.List ((\\)) import System.Random (randomRIO) import Data.Word (Word32) import Graphics.UI.SDL as SDL main = do SDL.init [InitVideo, InitTimer, InitEventthread] w <- setVideoMode 1440 900 32 [] setCaption "LIFE" "life" eventLoop w cells quit eventLoop w cs = do drawCells w cs e <- waitEventBlocking checkEvent e where checkEvent (KeyUp (Keysym SDLK_ESCAPE _ _)) = return () checkEvent (KeyUp (Keysym SDLK_n _ _)) = eventLoop w $ nextgen cs checkEvent _ = eventLoop w cs drawCells w cs = do clearScreen s <- createRGBSurface [SWSurface] size size 32 0 0 0 0 sequence $ map (draw s) $ scale cs SDL.flip w where clearScreen = fillRect w (Just $ Rect 0 0 1440 900) $ Pixel 0x0 rect x y = Just $ Rect x y size size scale = map (\(x,y) -> (x * size, y * size)) size = 16 draw s (x,y) = do r <- randomRIO (0::Int, 0xFFFFFF) fillRect s (rect 0 0) $ Pixel (fromIntegral r :: Word32) blitSurface s (rect 0 0) w $ rect x y -------------------------------------------------------------------------------- cells = [(25,14),(26,14),(25,15),(24,15),(25,16)] nextgen cs = (filter (live cs) cs) ++ births cs live cs c = size neighbors > 1 && size neighbors < 4 where neighbors = adj c `intersection` fromList cs births cs = (filter neighbors3 allAdjacent) \\ cs where allAdjacent = nub $ concatMap (toList . adj) cs neighbors3 c = size (neighbors c) == 3 neighbors c = adj c `intersection` fromList cs nub = toList . fromList adj (x,y) = fromList $ tail [(a,b) | a <- [x,x+1,x-1], b <- [y,y+1,y-1]]