examples/ex-60.rkt
#lang racket
(require (planet wcy/mpost-wrapper))
(provide main)
(define (main)
  (let* ((u '0.5cm)
         (A (point 0 0))
         (B (point (op* -1 u) (op* 2 u)))
         (C (point (op* 4  u) (op* 3 u)))
         (D (point (op* 3  u) 0)))
    (draw (path
           A ".." " controls " B " and " C ".." D)
          #:withpen (scale '2pt 'pencircle))
    (draw (op-- B C) #:dashed 'evenly)
    (drawarrow (op-- A B))
    (drawarrow (op-- D C))))