anchor.diff:      :initform nil)
      (vert-shader
       :reader vert-shader
  +    :initform nil)
  +   (geo-shader
  +    :reader geo-shader
       :initform nil)
      (attributes
       :reader attributes 
  
positive.code: 
    (with-slots ((vs vert-shader)
    	       (fs frag-shader)
    	       (program program)) this
      (setf vs (gl:create-shader :vertex-shader))
      (setf fs (gl:create-shader :fragment-shader))    
  
negative.code:       (gl:detach-shader program fs))
  
      (when vs (gl:delete-shader vs))
      (when fs (gl:delete-shader fs))
      (when geo (gl:delete-shader geo))
  
      (when program (gl:delete-program program))
  
  