Lisp list-contains program

Question

how can I make a Lisp program that checks if a character, string or number is in a list?

(list-contains '(1 a 2 d 2 5) 'a) => T

(list-contains '(1 a 2 d 2 5) 'x) => NIL

Answer 1

You can use (find x the-list) which returns x if x is in the list or NIL if it is not.

(find 'a '(1 a 2 d 2 5)) ; A
(find 'x '(1 a 2 d 2 5)) ; NIL