[plt-scheme] Making a fast list like sequence

On Tue, Apr 7, 2009 at 6:48 PM, Matthew Flatt <mflatt at cs.utah.edu> wrote:
> At Tue, 07 Apr 2009 18:32:33 -0400, David Van Horn wrote:
>> I see dramatic differences in running times between the built-in list
>> sequence and a naive implementation of list sequencing.  What can I do
>> to make this naive implementation run faster?
>
> If you use use `car', `cdr', and `pair? instead of `first', `rest', and
> `(compose not empty?)', you should get the same performance as for
> lists.

I can certainly see why pair? will be faster than (compose not
empty?), but why would car/cdr/pair?/null? be significantly faster
than first/rest/cons?/empty? ?  Is there extra contract wrapping or
something?

-- 
Carl Eastlund