anchor.diff:        (progn
           (match (setup-function minibuffer)
             ((guard f f) (funcall f minibuffer)))
  +        (state-changed minibuffer)
           (update-display minibuffer))
       (error (c)
         (echo "~a" c)
  
positive.code:   (with-slots (input-buffer input-cursor-position) minibuffer
      (when (< input-cursor-position (length input-buffer))
        (incf input-cursor-position)))
    (update-display minibuffer))
  
  (define-command cursor-backwards (&optional (minibuffer (current-minibuffer)))
  
negative.code:   "Select previous entry in minibuffer."
    (when (> (completion-cursor minibuffer) 0)
      (decf (completion-cursor minibuffer))
      (state-changed minibuffer)
      (update-display minibuffer)
      (evaluate-script minibuffer
                       (ps:ps (ps:chain (ps:chain document (get-element-by-id "head"))
  