(defvar *canvas* nil)
(defvar *context* nil)

(defun my-function ()
   (init-canvas)
   (draw-sine))

(defun init-canvas ()
   (progn (setf *canvas* (ps:chain document (get-element-by-id "example")))
	  (setf *context* (ps:chain *canvas* (get-context "2d")))
	  1))

(defun draw-sine ()
   (progn (ps:chain *context* (begin-path))
          (ps:chain *context* (move-to 0 512)) ; (= (sin 0) 0)
          (do ((angle 0 (+ angle (/ pi 50)))
               (x 0 (+ x 12)))
              ((>= angle (* 2 pi)))
	      (let ((y (+ (* 480 (sin angle)) 512)))
		   (ps:chain *context* (line-to x y))
		   (ps:chain *context* (move-to x y))))
	  (setf (ps:@ *context* stroke-style) "black")
	  (ps:chain *context* (stroke))
	  1))