77 lines
2.0 KiB
Haskell
77 lines
2.0 KiB
Haskell
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{-#LANGUAGE TypeSynonymInstances, FlexibleInstances#-}
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import Data.Maybe (listToMaybe)
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import Data.List (intercalate)
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data Mat a = Mat [[a]]
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type Pos = (Int, Int)
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type Grid = Mat Cell
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type Cell = Int
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instance Functor Mat where
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fmap f (Mat m) = Mat ((map . map) f m)
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instance Show Grid where
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show (Mat m) = concatMap ((++"\n") . intercalate " " . map replace) m
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where
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replace 1 = "■"
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replace 0 = "'"
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-- | Safely access a list
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-- [4,1,5,9] ?? 2 == Just 5
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-- [5,7] ?? 3 == Nothing
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(??) :: [a] -> Int -> Maybe a
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xs ?? n | n < 0 = Nothing
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[] ?? _ = Nothing
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(x:_) ?? 0 = Just x
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(_:xs) ?? n = xs ?? (n-1)
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-- | Create a Mat of Indeces for a grid
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indeces :: Grid -> Mat Pos
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indeces (Mat m) = Mat [[(x,y) | y <- [0..length (m !! x)-1]] |
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x <- [0..length m-1]]
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-- | Get the state of a cell
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-- 0 when out of the grid
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(!) :: Grid -> Pos -> Cell
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(Mat g) ! (x, y) = case g ?? y >>= (?? x) of
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Nothing -> 0
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Just v -> v
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-- | Create empty grid
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void :: Int -> Int -> Grid
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void x y = Mat (replicate x $ replicate y 0)
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-- | Give the list of neighbours cells
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near :: Grid -> Pos -> [Cell]
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near g (x, y) = [g ! (x+x', y+y') | x' <- [-1..1],
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y' <- [-1..1],
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(x',y') /= (0,0)]
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-- | Find if a cell will be alive in the next generation
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alive :: Grid -> Pos -> Cell
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alive g p
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| v == 0 && n == 3 = 1
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| v == 1 && (n == 2 || n == 3) = 1
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| otherwise = 0
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where
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(n, v) = (sum (near g p), g ! p)
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-- | Compute next generation
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next :: Grid -> Grid
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next g = fmap (alive g) (indeces g)
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main :: IO ()
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main = mapM_ print (iterate next grid)
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grid = Mat [
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[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
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, [0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0]
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, [0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0]
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, [0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0]
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, [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
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, [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
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, [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
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]
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