examples/ex-2.rkt
#lang racket
(require (planet wcy/mpost-wrapper))
(provide main)
(define (A-B-C)
  (values (point 0 0)
          (point '1cm 0)
          (point 0 '1cm)))
(define (main)
  (draw
   (call-with-values A-B-C
     (lambda (A B C)
       (op-- A B C 'cycle)))))