(define traverse
  (letrec
    ([traverse
       (lambda (t s)
	 (cond
	   [(null? t) (CONS '() s)]
	   [(integer? t)
	    (let ([m (max t s)])
	      (CONS m m))]
	   [else 
	     (let ([pr (traverse (car t) s)])
	       (let ([pr-d (traverse (cdr t) (CDR pr))])
		 (CONS (cons (CAR pr) (CAR pr-d)) (CDR pr-d))))]))])
    (lambda (t)
      (CAR (traverse t 0)))))

(define test-traverse
  (lambda ()
    (traverse '((((2 4 (1 5 3) 7 6) 4) 2 4)))))

(pretty-print (test-traverse)) (newline)

(define unit   
  (lambda (v)     
    (lambda (s)
      (CONS v s)))) 
                       
(define unit-max
  (lambda (v)
    (lambda (s)
      (let ([m (max v s)])  
        (CONS m m)))))       

(define bind
  (lambda (m w)
    (lambda (s)
      (let ([pr (m s)])
        ((w (CAR pr)) (CDR pr))))))

(define traverse
  (letrec
    ([traverse
       (lambda (t)
	 (cond
	   [(null? t) (unit '())]
	   [(integer? t) (unit-max t)]
	   [else
	     (bind
	       (traverse (car t))
	       (lambda (a)
		 (bind
		   (traverse (cdr t))
		   (lambda (d)
		     (unit (cons a d))))))]))])
    (lambda (t)
      (CAR ((traverse t) 0)))))

(pretty-print (test-traverse)) (newline)

(define traverse
  (letrec
    ([traverse
       (lambda (t)
	 (cond
	   [(null? t) (unit '())]
	   [(integer? t) (unit-max t)]
	   [else
	     (bind
	       (traverse (car t))
	       (lambda (a)
		 (bind
		   (traverse (cdr t))
		   (lambda (d)
		     ((lambda (v)     
			(lambda (s)
			  (CONS v s)))
		      (cons a d))))))]))])
    (lambda (t)
      (CAR ((traverse t) 0)))))

(pretty-print (test-traverse)) (newline)

(define traverse
  (letrec
    ([traverse
       (lambda (t)
	 (cond
	   [(null? t) (unit '())]
	   [(integer? t) (unit-max t)]
	   [else
	     (bind
	       (traverse (car t))
	       (lambda (a)
		 (bind
		   (traverse (cdr t))
		   (lambda (d)
		     (lambda (s)
		       (CONS (cons a d) s))))))]))])
    (lambda (t)
      (CAR ((traverse t) 0)))))

(pretty-print (test-traverse)) (newline)

(define traverse
  (letrec
    ([traverse
       (lambda (t)
	 (cond
	   [(null? t) (unit '())]
	   [(integer? t) (unit-max t)]
	   [else
	     (bind
	       (traverse (car t))
	       (lambda (a)
		 ((lambda (m w)
		    (lambda (s)
		      (let ([pr (m s)])
			((w (CAR pr)) (CDR pr)))))
		  (traverse (cdr t))
		  (lambda (d)
		    (lambda (s)
		      (CONS (cons a d) s))))))]))])
    (lambda (t)
      (CAR ((traverse t) 0)))))

(pretty-print (test-traverse)) (newline)

(define traverse
  (letrec
    ([traverse
       (lambda (t)
	 (cond
	   [(null? t) (unit '())]
	   [(integer? t) (unit-max t)]
	   [else
	     (bind
	       (traverse (car t))
	       (lambda (a)
		 (lambda (s)
		   (let ([pr ((traverse (cdr t)) s)])
		     (((lambda (d)
			 (lambda (s)
			   (CONS (cons a d) s)))
		       (CAR pr))
		      (CDR pr))))))]))])
    (lambda (t)
      (CAR ((traverse t) 0)))))

(pretty-print (test-traverse)) (newline)

(define traverse
  (letrec
    ([traverse
       (lambda (t)
	 (cond
	   [(null? t) (unit '())]
	   [(integer? t) (unit-max t)]
	   [else
	     (bind
	       (traverse (car t))
	       (lambda (a)
		 (lambda (s)
		   (let ([pr ((traverse (cdr t)) s)])
		     ((lambda (s)
			(CONS (cons a (CAR pr)) s))
		      (CDR pr))))))]))])
    (lambda (t)
      (CAR ((traverse t) 0)))))

(pretty-print (test-traverse)) (newline)

(define traverse
  (letrec
    ([traverse
       (lambda (t)
	 (cond
	   [(null? t) (unit '())]
	   [(integer? t) (unit-max t)]
	   [else
	     (bind
	       (traverse (car t))
	       (lambda (a)
		 (lambda (s)
		   (let ([pr ((traverse (cdr t)) s)])
		     (CONS (cons a (CAR pr)) (CDR pr))))))]))])
    (lambda (t)
      (CAR ((traverse t) 0)))))

(pretty-print (test-traverse)) (newline)

(define traverse
  (letrec
    ([traverse
       (lambda (t)
	 (cond
	   [(null? t) (unit '())]
	   [(integer? t) (unit-max t)]
	   [else
	     ((lambda (m w)
		(lambda (s)
		  (let ([pr (m s)])
		    ((w (CAR pr)) (CDR pr)))))
	      (traverse (car t))
	      (lambda (a)
		(lambda (s)
		  (let ([pr ((traverse (cdr t)) s)])
		    (CONS (cons a (CAR pr)) (CDR pr))))))]))])
    (lambda (t)
      (CAR ((traverse t) 0)))))

(pretty-print (test-traverse)) (newline)

(define traverse
  (letrec
    ([traverse
       (lambda (t)
	 (cond
	   [(null? t) (unit '())]
	   [(integer? t) (unit-max t)]
	   [else
	     (lambda (s)
	       (let ([pr ((traverse (car t)) s)])
		 (((lambda (a)
		     (lambda (s)
		       (let ([pr ((traverse (cdr t)) s)])
			 (CONS (cons a (CAR pr)) (CDR pr)))))
		   (CAR pr))
		  (CDR pr))))]))])
    (lambda (t)
      (CAR ((traverse t) 0)))))

(pretty-print (test-traverse)) (newline)

(define traverse
  (letrec
    ([traverse
       (lambda (t)
	 (cond
	   [(null? t) (unit '())]
	   [(integer? t) (unit-max t)]
	   [else
	     (lambda (s)
	       (let ([pr ((traverse (car t)) s)])
		 ((lambda (s)
		    (let ([pr-d ((traverse (cdr t)) s)])
		      (CONS (cons (CAR pr) (CAR pr-d)) (CDR pr-d))))
		  (CDR pr))))]))])
    (lambda (t)
      (CAR ((traverse t) 0)))))

(pretty-print (test-traverse)) (newline)

(define traverse
  (letrec
    ([traverse
       (lambda (t)
	 (cond
	   [(null? t) (unit '())]
	   [(integer? t) (unit-max t)]
	   [else
	     (lambda (s)
	       (let ([pr ((traverse (car t)) s)])
		 (let ([pr-d ((traverse (cdr t)) (CDR pr))])
		   (CONS (cons (CAR pr) (CAR pr-d)) (CDR pr-d)))))]))])
    (lambda (t)
      (CAR ((traverse t) 0)))))

(pretty-print (test-traverse)) (newline)

(define traverse
  (letrec
    ([traverse
       (lambda (t)
	 (cond
	   [(null? t) (unit '())]
	   [(integer? t)
	    ((lambda (v)
	       (lambda (s)
		 (let ([m (max v s)])
		   (CONS m m))))
	     t)]
	   [else
	     (lambda (s)
	       (let ([pr ((traverse (car t)) s)])
		 (let ([pr-d ((traverse (cdr t)) (CDR pr))])
		   (CONS (cons (CAR pr) (CAR pr-d)) (CDR pr-d)))))]))])
    (lambda (t)
      (CAR ((traverse t) 0)))))

(pretty-print (test-traverse)) (newline)

(define traverse
  (letrec
    ([traverse
       (lambda (t)
	 (cond
	   [(null? t) (unit '())]
	   [(integer? t)
	    (lambda (s)
	      (let ([m (max t s)])
		(CONS m m)))]
	   [else
	     (lambda (s)
	       (let ([pr ((traverse (car t)) s)])
		 (let ([pr-d ((traverse (cdr t)) (CDR pr))])
		   (CONS (cons (CAR pr) (CAR pr-d)) (CDR pr-d)))))]))])
    (lambda (t)
      (CAR ((traverse t) 0)))))

(pretty-print (test-traverse)) (newline)

(define traverse
  (letrec
    ([traverse
       (lambda (t)
	 (cond
	   [(null? t)
	    ((lambda (v)
	       (lambda (s)
		 (CONS v s)))
	     '())]
	   [(integer? t)
	    (lambda (s)
	      (let ([m (max t s)])
		(CONS m m)))]
	   [else
	     (lambda (s)
	       (let ([pr ((traverse (car t)) s)])
		 (let ([pr-d ((traverse (cdr t)) (CDR pr))])
		   (CONS (cons (CAR pr) (CAR pr-d)) (CDR pr-d)))))]))])
    (lambda (t)
      (CAR ((traverse t) 0)))))

(pretty-print (test-traverse)) (newline)

(define traverse
  (letrec
    ([traverse
       (lambda (t)
	 (cond
	   [(null? t)
	    (lambda (s)
	      (CONS '() s))]
	   [(integer? t)
	    (lambda (s)
	      (let ([m (max t s)])
		(CONS m m)))]
	   [else
	     (lambda (s)
	       (let ([pr ((traverse (car t)) s)])
		 (let ([pr-d ((traverse (cdr t)) (CDR pr))])
		   (CONS (cons (CAR pr) (CAR pr-d)) (CDR pr-d)))))]))])
    (lambda (t)
      (CAR ((traverse t) 0)))))

(pretty-print (test-traverse)) (newline)

(define traverse
  (letrec
    ([traverse
       (lambda (t)
	 (lambda (s)
	   (cond
	     [(null? t) (CONS '() s)]
	     [(integer? t)
	      (let ([m (max t s)])
		(CONS m m))]
	     [else
	       (let ([pr ((traverse (car t)) s)])
		 (let ([pr-d ((traverse (cdr t)) (CDR pr))])
		   (CONS (cons (CAR pr) (CAR pr-d)) (CDR pr-d))))])))])
    (lambda (t)
      (CAR ((traverse t) 0)))))

(pretty-print (test-traverse)) (newline)

(define traverse
  (letrec
    ([traverse
       (lambda (t s)
	 (cond
	   [(null? t) (CONS '() s)]
	   [(integer? t)
	    (let ([m (max t s)])
	      (CONS m m))]
	   [else
	     (let ([pr (traverse (car t) s)])
	       (let ([pr-d (traverse (cdr t) (CDR pr))])
		 (CONS (cons (CAR pr) (CAR pr-d)) (CDR pr-d))))]))])
    (lambda (t)
      (CAR (traverse t 0)))))

(pretty-print (test-traverse)) (newline)