[plt-scheme] version 4 (4.1.3) newbie question

http://blog.plt-scheme.org/2007/11/getting-rid-of-set-car-and-set-cdr.html

"Of course, PLT Scheme v4.0 will support an R5RS language where cons is 
mcons, and so on, so many old programs can still run easily in the new 
version. The difference is that interoperability between R5RS libraries 
and PLT Scheme libraries will be less direct than before."

Chongkai

Johannes Brauer wrote:
>   Hi,
> if I put
>
> #lang scheme
>
> (list? (cons 1 '()))
> (filter (lambda (x) (> x 5)) '(3 5 6 7))
>
> in the definition pane of DrScheme I get in the interaction pane:
> #t
> (6 7)
>
> Fine! But  putting
> #lang scheme
> (require r5rs/init)
>
> (list? (cons 1 '()))
> (filter (lambda (x) (> x 5)) '(3 5 6 7))
>
> in the definition pane I get an error message:
>
> filter: expected argument of type <proper list>; given (3 5 6 7)
>
> Can anyone explain me that?
>
> Thanks
> Johannes
>
>
>
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