(define title "Snake Game")

;; We have figured out the constants of the Snake world.

;; We have settled on a data representation for the Snake world and all of
;; its pieces.

;; It's time to create a wishlist of functions.

(define-struct world (snake food))
(define-struct food (x y))
(define-struct snake (dir seg))

#|  
-----------------------------------------------------------------------------
Snake World
----------

World is a structure: (make-world Snake Food)

Food is a structure: (make-food Number Number)

Snake is a structure: (make-snake Direction Segments)

Direction is one of the following symbols:
-- 'up
-- 'down
-- 'left
-- 'right

Segments is one of:
-- empty
-- (cons Posn Segments)
|#

;; Start with the world, when you make up a wish list, the others will fall
;; out. This should suggest something like that.

;; world-draw : World -> Image
;; world-move : World -> World

;; snake-draw : Snake -> Image
;; snake-move : Snake -> Snake
;; snake-change-direction : Snake Direction -> Snake
;; snake-eat : Snake Food -> Snake

;; food-draw : Food -> Image

;; Add purpose statements. Then pick a place and start.