How to sum a list of numbers in Emacs Lisp?

Question

This works:

(+ 1 2 3) 6 

This doesn't work:

(+ '(1 2 3)) 

This works if 'cl-*' is loaded:

(reduce '+ '(1 2 3)) 6 

If reduce were always available I could write:

(defun sum (L)   (reduce '+ L))  (sum '(1 2 3)) 6 

What is the best practice for defining functions such as sum?

Answer 1

(apply '+ '(1 2 3)) 

Answer 2

If you manipulate lists and write functional code in Emacs, install dash.el library. Then you could use its -sum function:

(-sum '(1 2 3 4 5)) ; => 15