Game of life in Haskell (in 45 minutes)

gol.hs

zeroes 0 = []
zeroes n = [0] ++ (zeroes (n-1))

foo x y z= zipWith (+) (zipWith (+) x y) z

grid_neighbours l =
  let top = map inc_neighbours ( [(zeroes (length (head l)))] ++ (take (length l) l) )
      bottom = map inc_neighbours ((drop 1 l) ++ [(zeroes (length (head l)))])
      current = map neighbours l
  in zipWith3 foo top bottom current 

inc_neighbours l = zipWith (+) (neighbours l) l

neighbours l = 
  let right = (drop 1 l) ++ [0]
      left = [0] ++ (take (length l) l)
  in zipWith (+) left right
  
next_state cs nr
  | cs == 1 && (nr == 2 || nr == 3 )= 1
  | cs == 0 && nr == 3 = 1
  | otherwise = 0

make_step l= zipWith make_row_step l (grid_neighbours l)

make_row_step l r = zipWith next_state l r