Snake in Elm

gistfile1.elm

import Keyboard
import Window

startPos = {x = 10, y = 10}
startDir = {x = 1, y = 0}
dir = foldp rotate startDir Keyboard.arrows
rotateLeft p = {x=p.y * (0-1), y=p.x}
rotateRight p = {x=p.y, y=p.x * (0-1)}
rotate dir p = if | dir.x < 0 -> rotateLeft p
                  | dir.x > 0 -> rotateRight p
                  | otherwise -> p
pos = let plus a b = {x=a.x+b.x,y=a.y+b.y} in
  (foldp plus startPos (sampleOn (fps 2) dir))
snake = slidingWindow 5 pos
renderDot (w,h) color pos = rect 10 10 |> filled color |> move (pos.x * 10, pos.y * 10)

renderSnake (w,h) snake = 
  let snakeDots = map (renderDot (w,h) (rgb 240 50 50 )) snake
  in collage w h snakeDots
  
main = lift2 renderSnake Window.dimensions snake

slidingWindow max s =
  let limit xs = take max xs
      window x xs = limit (x :: xs)
  in foldp window [] s