;;***KOLEJKA************************************************************
;;Implementacja Kolejki
(define-unit bag-fifo@
  (import)
  (export bag^)

  (define (bag? x)
    (and (list? x)
         (eq? (length x) 2)
         (eq? (car x) 'bag-fifo)))

   (define (bag-empty? x)
    (eq? (bag-fifo x) '()))

  (define (bag-fifo x) (cadr x))
  (define (bag-cons l) (list 'bag-fifo l))

  (define empty-bag (bag-cons '()))

  (define (bag-peek x) (car (reverse (bag-fifo x))))

  (define (bag-remove x)
    (bag-cons (reverse (cdr (reverse (bag-fifo x))))))

  (define (bag-insert x v)
    (bag-cons (cons v (bag-fifo x)))))

;;Otwarcie implamentacji Kolejki
(define-values/invoke-unit/infer bag-fifo@)

(define my-fifo empty-bag)