membership predicate
Major Section:  PROGRAMMING

(Member-equal x lst) equals the longest tail of lst that begins with x, or else nil if no such tail exists.

(Member-equal x lst) has a guard of (true-listp lst). Member-equal has the same functionality as the Common Lisp function member, except that it uses the equal function to test whether x is the same as each successive element of lst. See member and see member-eq.