(define (random-int min max)
  (+ min (random (+ 1 (- max min)))))

(define (draw-samples seq length maxlength)
  (lazy-take
    (or length (and max (random maxlength))) seq))


(define (make-number-seq min max filter succ)
  (let ((seq (lazy-filter filter (lazy-iterate succ min))))
    (if max
        (lazy-take (+ 1 (- max min)) seq)
        seq)))

(define (gen-fixnum/random #!key (min 0) (max 39085789345) (filter (constantly #t)) (after identity))
  (let ((next (lambda _ (after (random-int min max)))))
    (make-number-seq (next) max filter next)))

;; list
(define (gen-list generator #!key (max 10) (length #f))
  (lazy-repeatedly
   (lambda ()
     (lazy-seq->list
      (draw-samples generator length max)))))