object—an object.
generalized-boolean—a generalized boolean.
Returns true if object is of type list
;
otherwise, returns false.
(listp nil) → true (listp (cons 1 2)) → true (listp (make-array 6)) → false (listp t) → false
If object is a cons,
listp
does not check whether object is a proper list;
it returns true for any kind of list.
(listp object) ≡ (typep object 'list) ≡ (typep object '(or cons null))