(define Point%
  (class object%
    (super-new)
    (init-field x y)
    
    (public get-x get-y normalize translate)
    
    (define (get-x) x)
    (define (get-y) y)
    
    (define (normalize)
      (let* ([x x]
             [y y]
             [scale (sqrt (+ (* x x) (* y y)))])
        (new Point% [x (/ x scale)] [y (/ y scale)])))
    
    (define (translate dx dy)
      (new Point% [x (+ x dx)] [y (+ y dy)]))))

(define Polygon%
  (class object%
    (super-new)
    
    (define vertices (vector))
    
    (public add-vertex translate)
    
    (define (add-vertex v)
      (set! vertices
            (list->vector (append (vector->list vertices)
                                  (list v)))))
    
    (define (translate dx dy)
      (let* ([vs vertices]
             [size (vector-length vs)])
        (let loop ([i 0])
          (when (< i size)
            (vector-set! vs i (send (vector-ref vs i) translate dx dy))
            (loop (+ i 1))))))))

(define (complex-picture)
  (send* (new Polygon%)
    (add-vertex (new Point% [x 0] [y 0]))
    (add-vertex (new Point% [x 5] [y 0]))
    (add-vertex (new Point% [x 0] [y 5]))
    (translate 5 5)))

(define (simple-picture)
  (send (new Point% [x 1.0] [y 1.0]) normalize))