[plt-scheme] side effects in R6RS modules

At Sun, 03 May 2009 08:53:21 -0600, Chongkai Zhu wrote:
> Michele Simionato wrote:
> > (define-syntax define+
> >  (lambda (x)
> >    (syntax-case x ()
> >      ((define+ name value)
> >       #'(begin
> >           ;; dirty trick to get an expand time side effect
> >           (define-syntax dummy (begin (register #'name) (lambda (x) #f)))
> >           ;; the real definition
> >           (define name value))))))
> >   
> 
> Why the dirty trick? This works:
> 
> (define-syntax define+
>   (lambda (x)
>     (syntax-case x ()
>       ((define+ name value)
>        (begin (register #'name)
>               #'(define name value))))))

No, this does not work. The reasons is explained in the "Composable and
Compilable Macros" paper that Michele cited.