Figures as Lists of Lines

left top right

(define (figure-length figure)
  (if (no-more-lines? figure)
      0
      (+ (line-length (first-line figure))
	 (figure-length (rest-of-lines figure)))))

(define (no-more-lines? f) (null? f))
(define (first-line f) (car f))
(define (rest-of-lines f) (cdr f))

Jim Miller W3C