anchor.diff:  ;;; main
   ;;;
   
  +#|
  +(require :sb-sprof)
  +(defun main/profile ()
  +  (sb-sprof:with-profiling (:max-samples 1000
  +                            :report      :graph
  +                            :loop        nil)
  +    (setf *gpu* nil)
  +    (main)))
  +|#
  +
   (defun main ()
     (setf glut:*run-main-loop-after-display* nil)
     (let ((window (make-instance 'nbody-window)))
  
positive.code:      (declare (type single-float ,x ,y ,z))
       ,@body))
  
  (defun vec3-array-values (ary i)
    (declare (optimize (speed 3) (safety 0)))
    (declare (type vec3-array ary)
  
negative.code:   ;; for fast write
    `(%set-vec3-array ,ary ,i ,x ,y ,z))
  
  (declaim (inline %set-vec3-array))
  (defun %set-vec3-array (ary i x y z)
    (declare (optimize (speed 3) (safety 0)))
    (declare (type vec3-array ary)
  