run-with-timer error: “Invalid or unitialized timer”

Question

I am trying to create a simple timer.

All I am doing is C-x-e-ing this expression:

(run-with-timer (* 60 25) nil (insert "Success!"))

Problem is I get an error message:

 Debugger entered--Lisp error: (error "Invalid or uninitialized timer")
  signal(error ("Invalid or uninitialized timer"))
  error("Invalid or uninitialized timer")
  timer--activate([t 21693 2834 932492 nil nil nil nil 0] nil nil nil)
  timer-activate([t 21693 2834 932492 nil nil nil nil 0])
  run-at-time(10 nil nil)
  apply(run-at-time 10 nil nil nil)
  run-with-timer(10 nil nil)
  eval((run-with-timer 10 nil (insert "Success!")) nil)
  elisp--eval-last-sexp(nil)
  eval-last-sexp(nil)
  funcall-interactively(eval-last-sexp nil)
  call-interactively(eval-last-sexp nil nil)
  command-execute(eval-last-sexp)

The error message stems from this line in the Emacs source.

How can I fix this and create a simple timer for myself?

Ps. here is the apropos for run-with-timer:

run-with-timer is an interactive compiled Lisp function in `timer.el'.

(run-with-timer SECS REPEAT FUNCTION &rest ARGS)

Perform an action after a delay of SECS seconds.
Repeat the action every REPEAT seconds, if REPEAT is non-nil.
SECS and REPEAT may be integers or floating point numbers.
The action is to call FUNCTION with arguments ARGS.

This function returns a timer object which you can use in `cancel-timer'.

This worked for some reason:

(run-with-timer 0 10 'oo) 

(defun oo ()
  (message "message 10 secs"))

Can anyone explain why? I guess a function and a function name aren't interchangeable everywhere.

Answer 1

The documentation has the answer. The third arg must be a function, (insert "success") is not a function, it is an expression.

Try (lambda () (insert "success"))