(load "leaf.ss")

;; compare Program 7.25

(define filter-in-all-c
  (lambda (pred)
    (letrec
      ((helper 
	; TYPE: tree of a -> tree of a
         (lambda (ls)
           (if (null? ls)
               '()
               (let ((a (car ls)))
		 (if (leaf? a)
                     (if (pred a)
                         (cons a
			       (helper
				(cdr ls)))
                         (helper (cdr ls)))
		     (cons (helper a)
			   (helper
			     (cdr ls))))
		 )))))
      helper)))