I have written a small code that simulates the Game of Life by John Conway. This is the code:

import Control.Concurrent
import System.Random
import Control.Monad

data Cell = Alive | Dead  deriving Eq
instance Show Cell where
    show Alive = "X"
    show Dead = "0"

toCells :: [Int] -> [Cell]
toCells arr = (\ x -> if x==1 then Alive else Dead) <$> arr

getValue :: [Cell] -> Int -> Int -> Int -> Int -> Int
getValue state w h x y = 
    if x>=0 && x < w && y>=0 && y<h 
        then case state !! (y*w + x) of 
            Dead -> 0
            Alive -> 1
    else 0

countNeighbours :: [Cell] -> Int -> Int -> Int -> Int -> Int
countNeighbours state w h x y = sum $ (uncurry $ getValue state w h) <$> [(x,y+1),(x,y-1),(x+1,y+1),(x+1,y),(x+1,y-1),(x-1,y+1),(x-1,y),(x-1,y-1)]

newCell :: [Cell] -> Int -> Int -> Int -> Int -> Cell
newCell state w h x y = 
    if state !! (y*w + x) == Alive 
        then if countNeighbours state w h x y == 3 || countNeighbours state w h x y == 2 then Alive else Dead
        if countNeighbours state w h x y == 3 then Alive else Dead

clock :: [Cell] -> Int -> Int ->Int -> Int -> [Cell]
clock state x y w h = 
    if x == w-1 
        then if y == h-1 then [newCell state w h x y] else [newCell state w h x y] ++ clock state 0 (y+1) w h
    else [newCell state w h x y] ++ clock state (x+1) y w h

coolPrint :: [Cell] -> Int -> String
coolPrint [] w = "----------------"
coolPrint arr w = (show $ take w arr) ++ "\n" ++ coolPrint (drop w arr) w

update state w h= do
    threadDelay 1000000
    putStr "\ESC[2J"
    putStrLn $ coolPrint state w
    update (clock state 0 0 w h) w h

input = replicateM 625 (randomRIO (0,1))

runGame = do
    s <- input
    update (toCells s) 25 25

I have to admit, I am not very proud of it... Perhaps the update and clock functions could be implemented using the StateT monad, giving it a cleaner look. The cell data seems redundant and useless. What do you think? Any suggestion?


migrated from stackoverflow.com Feb 10 at 12:35

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