anchor.diff:  
   (define-command delete-forwards (&optional (minibuffer (current-minibuffer)))
     "Delete character after cursor."
  -  (with-slots (input-buffer input-buffer-cursor) minibuffer
  -    (unless (= input-buffer-cursor (length input-buffer))
  -      (setf input-buffer
  +  (with-accessors ((buffer input-buffer) (cursor input-buffer-cursor)) minibuffer
  +    (unless (= cursor (length buffer))
  +      (setf buffer
               (concatenate 'string
  -                         (subseq input-buffer 0 input-buffer-cursor)
  -                         (subseq input-buffer
  -                                 (+ 1 input-buffer-cursor)
  -                                 (length input-buffer))))))
  +                         (subseq buffer 0 cursor)
  +                         (subseq buffer
  +                                 (+ 1 cursor)
  +                                 (length buffer))))))
     (update-display minibuffer))
   
   (define-command delete-backwards (&optional (minibuffer (current-minibuffer)))
     "Delete character before cursor."
  -  (with-slots (input-buffer input-buffer-cursor) minibuffer
  -    (unless (= input-buffer-cursor 0)
  -      (setf input-buffer
  +  (with-accessors ((buffer input-buffer) (cursor input-buffer-cursor)) minibuffer
  +    (unless (= cursor 0)
  +      (setf buffer
               (concatenate 'string
  -                         (subseq input-buffer 0 (- input-buffer-cursor 1))
  -                         (subseq input-buffer input-buffer-cursor (length input-buffer))))
  -      (decf input-buffer-cursor)))
  +                         (subseq buffer 0 (- cursor 1))
  +                         (subseq buffer cursor (length buffer))))
  +      (decf cursor)))
     (update-display minibuffer))
   
   (define-command cursor-forwards (&optional (minibuffer (current-minibuffer)))
  
positive.code: 
  (define-command cursor-backwards (&optional (minibuffer (current-minibuffer)))
    "Move cursor backwards by one."
    (with-slots (input-buffer input-buffer-cursor) minibuffer
      (when (> input-buffer-cursor 0)
        (decf input-buffer-cursor)))
    (update-display minibuffer))
  
negative.code: @export
  (defmethod update-display ((minibuffer minibuffer))
    (with-slots (input-buffer input-buffer-cursor completion-function
                 completions completion-cursor empty-complete-immediate)
        minibuffer
      (if completion-function
          (setf completions (funcall completion-function input-buffer))
  