[racket] can't cdr list from dotted-tail notation?

[Sanjeev K Sharma]

I already spent a couple of hours on this, hope I am not missing something 
really obvious - does the dotted notation produce some kind of flat list 
instead of cons cells?



(define list-rf (lambda ( n . items )
  (if (= n 0)
      (car items)
      (list-rf (- n 1)(cdr items)))))

(list-rf 3 1 4 9 16 25 1 4 9 16 25 1 4 9 16 25 1 4 9 16 25)

output: '()

If I try to end the recursion on (null? items) it goes into an infinite loop


(define test2 (lambda  y
                (if (or(null? y)(null? (cdr y)))
                  y
                  (printf"~a~n"(cons (car y) (test2 (cdr y)))))))



(test2 1 2 3 4 5 6 7);&rArr;     <i>(1 3 5 7)</i>
(trace test2)

output:
{2 {3 4 5 6 7}}
{1 {2 3 4 5 6 7}}

and test2 doesn't recur.  If I replace that (if (or (null ...
with
         (if (null? y)

one last test 

(define test (lambda y
 (if(begin
             (printf"~a:list  ~a:null   ~a:len  ~n"(list? y)(null? y)(length y))
       (printf"~a:~n"y)
       (null? y))
    (printf"done")
    (if(> (car y) 9)
       #f
    (begin
     (printf"~a:~n"y)
     (test (cdr y)))))))
(test 2 3 4 5 6 7 2 3 4 5 6 7 2 3 4 5 6 7 999);

output: how does it go from length 17 to length  1 with one cdr? 

#t:list  #f:null   19:len  
{2 3 4 5 6 7 2 3 4 5 6 7 2 3 4 5 6 7 999}:
{2 3 4 5 6 7 2 3 4 5 6 7 2 3 4 5 6 7 999}:
#t:list  #f:null   1:len  
{{3 4 5 6 7 2 3 4 5 6 7 2 3 4 5 6 7 999}}:
. . >: contract violation
  expected: real?
  given: (mcons 3 (mcons 4 (mcons 5 (mcons 6 (mcons 7 (mcons 2 (mcons 3 (mcons 
4 (mcons 5 (mcons 6 (mcons 7 (mcons 2 (mcons 3 (mcons 4 (mcons 5 (mcons 6 
(mcons 7 (mcons 999 '()))))))))))))))))))
  argument position: 1st
  other arguments...:
   9
> 



the prompt never returns.

it's confusing the heck out of me.
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