examples/ex-123.rkt
#lang racket
(require (planet wcy/mpost-wrapper))
(provide main)
(define (main)
  (let* ((p (op.. (point 0 0)
                  (point '-1cm '2cm)
                  (point '2cm '1cm)
                  (point '1cm 0)))
         (n 10)
         (length-p (length p)))
    (draw p)
    (for ((i (in-range 0 1 (/ 1 n))))
         (let ((pi (point-of (op* i length-p) p)))
           (drawarrow (op-- pi
                            (shift pi (op* '1cm (unitvector (direction-of (op* i length-p) p))))))))))