Scheme nightmare

[Nighty]

EDITTED: SOLVED can someone delete/lock posted I am sorry......



I was given a Scheme homework. This is my first time programming in Scheme. I program in C++. So I have some programming knowledge. I am not asking any of you to do it or an answer for it. I just need help understanding why my code is acting up.

I am using the program Dr. Scheme.

This is the assignment:
Define a procedure (rac) which returns the LAST element of a list (RAC is CAR spelled backwards)

Example: (RAC (LIST 'A 'B 'C)) -> C

(define rac (lambda ls 
                (COND ((null? ls) ls)
                (ELSE  (cons (rac (cdr ls)) () )))))

The above code just to get a understanding of how to get element is the list. I know cdr removes the first element of the list and returns the rest of the list. Also the above code if I try to test for the empty list only it doesn't return the empty list back either

I do know that (cons '(a) () ) will result with ((a)) a list within a list.

but it I try something simple like:

(define rac (lambda ls (cdr ls)))

I enter (rac '(a b)) I get back the empty List ().

If I Try (rac '(a b c d)) I get the empty list again.

I don't understand why. Can someone help me and point me in the right direction.

[Nighty]

I figured it out. I didn't have an extra () in my code.

Example (define rac (lambda (ls) (cdr ls)))

That was making things werid.

I am sorry for making this stupid post. ::slap:: Can someone delete or lock this thread up. Thanks.