LISP cdr function

Question

If I do

(setq x   '(NOT (NOT (NOT (NOT A)))) )

(cdr x) is (NOT (NOT (NOT A))))

but (cdr (cdr x)) is NIL

What's going on here?

markw · Accepted Answer · 2012-02-21T06:15:03.957

7

Um, it shouldn't. (cdr x) should give you '((NOT (NOT (NOT A)))). Which means (NOT (NOT (NOT A))) is the first element of (cdr x). When you cdr again it's on a one-element list, so you get nil '()

edited Feb 21 '12 at 06:15

answered Feb 21 '12 at 05:09

markw

620
3
14

2

And if you explain a little more, it will show why (cdr (cdr x)) is NIL. – leppie Feb 21 '12 at 05:52

LISP cdr function

1 Answers1