Except at the end of the list when the cdr contains nil, which is not a pointer but a special value. BTW (listp (cons 1 2)) => true so (cons 1 2) is indee

Except at the end of the list when the cdr contains nil, which is not a pointer but a special value. BTW (listp (cons 1 2)) => true so (cons 1 2) is indeed a list; it's just not a proper list.