anchor.diff:  		    (return-from fetch-memo-vector-entry (vector-entry-msg-cache entry))))
   	    nil)))))
   
  -
  -
   (defstruct (vector-entry (:type vector))
     args
     msg-cache)
  +
  +(declaim (inline add-entry-to-buzzword))
  +(defun add-entry-to-buzzword (cache buzzword args index)
  +  (declare (fixnum index))
  +  (let ((memo-vector (buzzword-memo-vector buzzword))
  +        (vector-entry (make-vector-entry 
  +                       :args (make-weak-pointer args)
  +                       :msg-cache cache)))
  +    (cond ((loop for i from index below (length (the simple-vector memo-vector))
  +              when (eql (elt (the simple-vector memo-vector) i) 0)
  +              do (progn
  +                   (setf (elt memo-vector i) vector-entry)
  +                   (return t))
  +              finally (return nil))
  +           t)
  +          ((loop for i from index downto 0
  +             when (eql (elt memo-vector i) 0)
  +             do (progn
  +                  (setf (elt memo-vector i) vector-entry)
  +                  (return t))
  +              finally (return nil))
  +           t)
  +          ((setf (elt memo-vector index) vector-entry)
  +           t))))
   
   (defun memoize-message-dispatch (buzzword args msg-list)
     (let ((msg-cache (create-message-cache buzzword msg-list))
  
positive.code: 
  (defun find-applicable-messages (buzzword args &key (errorp t))
    (declare (buzzword buzzword))
    (let* (;; This doesn't seem to be expensive at all..
  	 (relevant-args-length (the fixnum (arg-info-number-required (buzzword-arg-info buzzword))))
  	 ;; If I can avoid calling fetch-memo-vector-entry for singly-dispatched readers, that
  
negative.code:     (add-entry-to-buzzword msg-cache buzzword args maybe-index)
      msg-cache))
  
  (defun %find-applicable-messages  (buzzword args &key (errorp t))
    "Returns the most specific message using BUZZWORD and ARGS."
    (declare (list args))
    (if (null args)
        (buzzword-messages buzzword)
        (let ((selector (buzzword-name buzzword))
  