dr racket help:

Create a big-bang animation where the world is a list; animating more than one object. Use something similar to:

(define start-world (list ...))

; Signature: list -> list (define (tick-handler lst) ...) ; Signature: list -> image (define (draw-scene lst) ...)

(big-bang start-world (on-tick tick-handler) (on-draw draw-scene))

Hint: You can have anything in a list, including posns.

Hint: All handlers have to return new lists, except the on-draw handler of course.