copy-alist alist → new-alist

alist — an association list.

new-alist — an association list.

copy-alist returns a copy of alist.

The list structure of alist is copied, and the elements of alist which are conses are also copied (as conses only). Any other objects which are referred to, whether directly or indirectly, by the alist continue to be shared.

(defparameter *alist* (acons 1 "one" (acons 2 "two" '()))) 
*alist* → ((1 . "one") (2 . "two")) 
(defparameter *list-copy* (copy-list *alist*)) 
*list-copy* → ((1 . "one") (2 . "two")) 
(defparameter *alist-copy* (copy-alist *alist*)) 
*alist-copy* → ((1 . "one") (2 . "two")) 
(setf (cdr (assoc 2 *alist-copy*)) "deux") → "deux" 
*alist-copy* → ((1 . "one") (2 . "deux")) 
*alist* → ((1 . "one") (2 . "two")) 
(setf (cdr (assoc 1 *list-copy*)) "uno") → "uno" 
*list-copy* → ((1 . "uno") (2 . "two")) 
*alist* → ((1 . "uno") (2 . "two"))

copy-list