Partial implementation of snake logic in Haskell

snake.hs

move :: [(Int, Int)] -> Int -> Int -> [(Int, Int)]
move snake x y = 
  let (hx, hy) = head snake
      nx = hx + x
      ny = hy + y
      n = (nx, ny)
      in (n : (init snake), last snake)

isWall' :: Int -> Int -> (Int, Int) -> Bool
isWall w h (x, y)
  | x == 0 || x == w = True
  | y == 0 || y == h = True
  | otherwise = False

drawCell' :: [(Int, Int)] -> (Int, Int) -> Int -> Int -> (Int, Int) -> ()
drawCell' snake food w h coord
  | isWall w h coord = render coord '#'
  | coord == (head snake) = render 'S'
  | elem coord snake = render coord '|'
  | coord == food = render coord '$'
  | otherwise = render coord ' '

draw' :: [(Int, Int)] -> (Int, Int) -> Int -> Int -> ()
draw' snake food w h =
  let x' = [0..w]
      y' = [0..h]
      a = [(x, y) | x <- x', y <- y']
      in map_ drawCell' a