Emacs根据时间切换主题

(setq day-theme 'modus-operandi)
(setq dark-theme 'modus-vivendi)
(defun switch-theme ()
    (setq hour
          (string-to-number
            (substring (current-time-string) 11 13)))
    (if (member hour (number-sequence 6 18))
        (setq now day-theme)
      (setq now dark-theme))
    (load-theme now)
)
(run-with-timer 0 3600 'switch-theme)