An association list is a list representing a mapping from one set of values to another; any list whose elements are cons cells is an association list.
&key :test :test-not :key ¶This function searches the association list a-list for an
element whose CAR matches (in the sense of :test,
:test-not, and :key, or by comparison with eql)
a given item. It returns the matching element, if any,
otherwise nil. It ignores elements of a-list that
are not cons cells. (This corresponds to the behavior of
assq and assoc in Emacs Lisp; Common Lisp’s
assoc ignores nils but considers any other non-cons
elements of a-list to be an error.)
&key :test :test-not :key ¶This function searches for an element whose CDR matches item. If a-list represents a mapping, this applies the inverse of the mapping to item.
The cl-assoc-if, cl-assoc-if-not, cl-rassoc-if,
and cl-rassoc-if-not functions are defined similarly.
Two simple functions for constructing association lists are:
This is equivalent to (cons (cons key value) alist).
This is equivalent to (nconc (cl-mapcar 'cons keys values)
alist).