(load "leaf.ss")

;; compare Program 7.27, pg. 225

(define sum-all
  (letrec
      ((helper
	; TYPE: tree of number -> number
	(lambda (ls)
	  (if (null? ls)
	      0
	      (let ((a (car ls))) 
		(if (leaf? a)
		    (+ a
		       (helper (cdr ls)))
		    (+ (helper a)
		       (helper (cdr ls))))
		)))))
    helper))