#lang planet dyoo/whalesong (require (planet dyoo/whalesong/world) (planet dyoo/whalesong/image)) (define width 640) (define height 480) (define-struct posn (x y)) (define (mouse world x y type) (cond [(string=? type "move") (make-posn x y)] [else world])) (define (draw w) (place-image (circle 20 'solid 'red) (posn-x w) (posn-y w) (empty-scene width height))) (printf "let's see how this works.\n\n") (big-bang (make-posn 0 0) (on-mouse mouse) (to-draw draw))