I'm implementing Conway's Life in Haskell; my basic implementation is attached. Does anyone have suggestions for optimizations (or alternative representations)? It's interesting to note that the difference between this with no ghc optimization, -O, and -O2 is pretty striking; on my computer, it's about seven seconds, two seconds, and one second runtime, respectively. Abe module Main where import Data.Array.IArray import Data.Array.Unboxed import Data.Ix import System.Random type Grid = UArray (Int, Int) Int randomGrid :: (RandomGen g) => g -> Int -> Grid randomGrid g s = listArray b $ map (\x -> if x then 1 else 0) $ take (rangeSize b) $ randoms g where b = ((0,0),(s-1,s-1)) getCell :: Grid -> (Int, Int) -> Int getCell g c@(x,y) = if (x < xmin) || (x > xmax) || (y < ymin) || (y >= ymax) then 0 else g ! c where ((xmin, ymin), (xmax, ymax)) = bounds g update :: Grid -> Grid update g = array (bounds g) $ map aux $ assocs g where aux (c@(x,y),e) = let around = map (getCell g) $ filter (/= (x,y)) $ range ((x-1,y-1),(x+1,y+1)) in (c,rule (sum around) e) rule 2 e = e rule 3 e = 1 rule _ _ = 0 printGrid :: Grid -> IO () printGrid g = do let ((xmin, ymin), (xmax, ymax)) = bounds g mapM_ aux $ map (\x -> range ((x,ymin),(x,ymax))) [xmin..xmax] putStrLn "" where aux ixs = do mapM_ (putStr . show) $ map (g!) ixs putStrLn "" main :: IO () main = printGrid $ (iterate update (randomGrid (mkStdGen 0) 50)) !! 100