What is the role of the @ character in Emacs Lisp?

Question

As used for instance in this macro definition:

(defmacro with-eval-after-load-feature (feature &rest body)
  (declare (indent 1) (debug t))
  (let* ((fea         


        

Answer 1

Asking Emacs is always a sensible approach:

• C-hig (elisp) RET
• I @ RET

This shows you all the elisp manual's index entries for @ (one of which is the ,@ you were actually looking for).

Answer 2

It's used for splicing in backquoted expressions. See C-h i g (elisp) Backquote RET. For example:

elisp> `(1 2 ,(list 3 4))  ; no splicing => nested list
(1 2
   (3 4))

elisp> `(1 2 ,@(list 3 4)) ; splicing => flat list
(1 2 3 4)