#lang scheme

(define get-x 1)
(define get-y 2)
(define do-print 3)
(define add 4)

(define (displayln x)
  (display x)
  (newline))

(define (vector x y)
  (define (add-to other)
    (vector (+ x (other get-x)) (+ y (other get-y))))

  (lambda (message)
    (if (= message get-x)
        x
        (if (= message get-y)
            y
            (if (= message add)
                add-to
                (if (= message do-print)
                    ((lambda ()
                       (displayln x)
                       (displayln y)
                       (newline)))
                    ((lambda ()
                       (displayln -99)
                       0))))))))

(define v-1-7 (vector 1 7))
(displayln (v-1-7 get-x))
(displayln (v-1-7 get-y))
(v-1-7 do-print)

(define v-8-2 (vector 8 2))
(displayln (v-8-2 get-x))
(displayln (v-8-2 get-y))
(v-8-2 do-print)

(define v-9-9 ((v-8-2 add) v-1-7))
(v-9-9 do-print)