Error running timer (wrong-number-of-arguments equals 3)

Question

I am trying to automatically change my Emacs theme according to time set (Thanks to answer provided by Dan).

My code looks like this:

(setq emacs-curr-theme nil)
(setq emacs-light-theme 'faff)
(setq emacs-dark-theme 'atom-one-dark)

(defun emacs-synchronize-theme ()

  (let ((hour nil) (now nil))
    (progn (setq hour 
        (string-to-number 
            (substring (current-time-string) 11 13)))
    (if (member hour (number-sequence 7 13))
        (setq now emacs-light-theme)
        (setq now emacs-dark-theme))

    (if (equal now emacs-curr-theme now)
        nil
        (progn
          (setq emacs-curr-theme now)
          (load-theme emacs-curr-theme t))))))

(defun emacs-set-theme ()
  ;; Load theme only when using GUI
  (when (display-graphic-p)
      (run-with-timer 0 900 'emacs-synchronize-theme)))

When I am calling the function emacs-set-theme from my init.el, I am getting this error -

Error running timer 'emacs-synchronize-theme': (wrong-number-of-arguments equal 3)

I have no clue what I am doing wrong here. I have checked documentation for run-with-timer, but unable to figure out the problem by myself.

Answer 1

Your error is:

(equal now emacs-curr-theme now)

As equal takes two arguments, not three.

I used M-x toggle-debug-on-error before running your code to find that quickly:

Debugger entered--Lisp error: (wrong-number-of-arguments equal 3)
  (equal now emacs-curr-theme now)
  (if (equal now emacs-curr-theme now) nil (progn (setq emacs-curr-theme now) (load-theme emacs-curr-theme t)))
  (progn (setq hour (string-to-number (substring (current-time-string) 11 13))) (if (member hour (number-sequence 7 13)) (setq now emacs-light-theme) (setq now emacs-dark-theme)) (if (equal now emacs-curr-theme now) nil (progn (setq emacs-curr-theme now) (load-theme emacs-curr-theme t))))
  (let ((hour nil) (now nil)) (progn (setq hour (string-to-number (substring (current-time-string) 11 13))) (if (member hour (number-sequence 7 13)) (setq now emacs-light-theme) (setq now emacs-dark-theme)) (if (equal now emacs-curr-theme now) nil (progn (setq emacs-curr-theme now) (load-theme emacs-curr-theme t)))))
  emacs-synchronize-theme()
  apply(emacs-synchronize-theme nil)
  timer-event-handler([t 24378 24806 149715 900 emacs-synchronize-theme nil nil 39000])