consp
object ⇒ generalized-boolean
object—an object.
generalized-boolean—a generalized boolean.
Returns true if object is of type cons; otherwise, returns false.
(consp nil) ⇒ false (consp (cons 1 2)) ⇒ true
The empty list is not a cons, so
(consp '()) == (consp 'nil) ⇒ false
(consp object) == (typep object 'cons) == (not (typep object 'atom)) == (typep object '(not atom))