#lang racket (require (planet wcy/mpost-wrapper)) (provide main) (define (A-B-C-D) (values (point 0 0) (point '1cm 0) (point '1cm '1cm) (point 0 '1cm))) (define (main) (call-with-values A-B-C-D (lambda (A B C D) (fill (op-- A C B D 'cycle) #:withcolor (op* 0.8 'white)))))