#lang racket
(require [only-in plait test test/exn error print-only-errors])

(define (mk-o-state count)
  (lambda (m)
    (case m
      [(inc) (lambda () (set! count (+ count 1)))]
      [(dec) (lambda () (set! count (- count 1)))]
      [(get) (lambda () count)])))

(define-syntax snd
  (syntax-rules ()
    [(_ obj selector args ...)
     ((obj (quote selector)) args ...)]))

(test (let ([o (mk-o-state 5)])
        (begin (snd o inc) (snd o inc) (snd o dec)
               (snd o get)))
      6)