Figures as Lists of Lines

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(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