anchor.diff:      (sdl2:with-window (win :w *width* :h *height* :flags '(:shown :opengl))
         (sdl2:with-gl-context (gl-context win)
           (sdl2:gl-make-current win gl-context)
  +        (sdl2:hide-cursor)
           (init)
   
           (sdl2:with-event-loop (:method :poll)
  
positive.code: ;(in-package #:cl-foo)
  
  (require :sdl2)
  
  (defparameter *width* 1280)
  (defparameter *height* 720)
  (defparameter *scale* 10)
  (defparameter *x* (* *width* (/ *scale* *height*)))
  (defparameter *y* *scale*)
  
  (defun main-loop ()
    (defun keydown-actions (scancode)
  
negative.code:            (:keysym keysym)
             (keyup-actions (sdl2:scancode-value keysym)))
  
            ;; Used to draw a square.
            (:idle
             ()
             (gl:clear :color-buffer :depth-buffer)
             (gl:begin :quad-strip)
             (gl:material :front :ambient-and-diffuse #(1.0 0.0 0.0 1.0))
             (gl:vertex 0.0 1.0 2.0)
             (gl:vertex 1.0 1.0 2.0)
             (gl:vertex 1.0 0.0 2.0)
             (gl:vertex 0.0 0.0 2.0)
             (gl:end)
             (gl:flush)
             (sdl2:gl-swap-window win))
  