;; zadanie 1
(define (st-app2 f . xs)
  (define (helper lst s rs)
    (if (null? lst)
        (cons (reverse rs) s)
        (let ([rx ((car lst) s)])
          (helper (cdr lst) (res-state rx) (cons (res-val rx) rs)))))
  (lambda (s)
    (let ([rx (helper xs s '())])
      (res (apply f (car rx))
           (cdr rx)))))

(define (rename3 t)
  (define (rename-st t)
    (cond [(leaf? t)
           (st-app2 (lambda (x y) x)
                   get-st
                   (modify-st inc))]
          [(node? t)
           (st-app2 node
                   (rename-st (node-left  t))
                   (rename-st (node-right t)))]))
  (res-val ((rename-st t) 0)))

;; zadanie 2
;; generator liczb pseudolosowych
(define (rand max)
  (lambda (i)
    (let ([v (modulo (+ (* 1103515245 i) 12345) (expt 2 32))])
      (res (modulo v max) v))))


(define (rename-rand t)
  (define (rename-st t)
    (cond [(leaf? t)
           (st-app (lambda (x y) x)
                   get-st
                   (rand 100))]
          [(node? t)
           (st-app node
                   (rename-st (node-left t))
                   (rename-st (node-right t)))]))
  (res-val ((rename-st t) 0)))