main.hs

cls :: IO()
cls = putStr "\ESC[2J"

type Pos = (Int, Int)

writeat:: Pos -> String -> IO()
writeat p xs = do goto p 
                  putStr xs

goto:: Pos -> IO()
goto (x, y) = putStr ("\ESC["++ show y++";"++ show x ++ "H")

width:: Int
width = 200

height :: Int
height = 100

type Board = [Pos]


glider::Board
glider = [(4,2), (2,3),(4,3), (3,4),(4,4)]

showcells::Board ->IO()
showcells b = sequence_ [writeat p "0"| p<-b]

isAlive:: Board -> Pos -> Bool
isAlive b p = elem p b

isEmpty::Board -> Pos -> Bool
isEmpty b p = not (isAlive b p)

neighbs::Pos -> [Pos]
neighbs (x,y) = map wrap [(x-1, y-1), (x, y-1), (x+1, y-1),(x-1,  y),(x+1, y), (x-1, y+1), (x, y+1),(x+1, y+1)]

wrap:: Pos -> Pos
wrap (x, y) = (((x-1) `mod` width)+1, ((y-1) `mod` height) + 1)


liveneighbs::Board -> Pos -> Int
liveneighbs b = length . filter (isAlive b). neighbs

survivors::Board -> [Pos]
survivors b = [p | p <-b, elem (liveneighbs b p) [2,3]]

-- births:: Board -> [Pos]
-- births b = [(x, y) | x <- [1..width],
--                     y <- [1..height],
--                     isEmpty b (x, y),
--                     liveneighbs b (x, y)==3 ]

births:: Board -> [Pos]
births b = [p | p <- rmdups (concat (map neighbs b)), isEmpty b p, liveneighbs b p == 3]

rmdups:: Eq a => [a] -> [a]
rmdups [] = []
rmdups (x:xs) = x:rmdups (filter (/=x) xs)

nextgen::Board -> Board
nextgen b = survivors b ++ births b

life::Board -> IO()
life b = do cls
            showcells b
            wait 500000
            life (nextgen b)


wait::Int -> IO()
wait n = sequence_ [return ()| _<- [1..n]]

main::IO()
main = life glider