[plt-scheme] Macros in the same module

On Mon, May 11, 2009 at 1:15 PM, Eli Barzilay <eli at barzilay.org> wrote:
>
> This won't work because of a different reason -- the literals of a
> `case' expression are not expressions, so they're not macro expanded.
> It wouldn't make sense to make them expand, since
>
>  (case 'if [(if) 1])
>
> should return 1 instead of raising a syntax error.  If you want to
> compute the expressions that go into the literals, you can do that
> with a function (but this whole example can be done with a much
> simpler macro):
>
>  #lang scheme
>
>  (define-for-syntax (bar a)
>    (syntax-case a (else)
>      [(else body) #'(else body)]
>      [(n body)    #'((n) body)]))
>
>  (define-syntax (foo a)
>    (syntax-case a ()
>      [(_ name rules ...)
>       (with-syntax ([(branch ...) (map bar (syntax->list #'(rules ...)))])
>         #'(case name branch ...))]))
>
>  (define op 0)
>
>  (foo op
>       (0 'zero)
>       (1 'one)
>       (2 'two)
>       (else 'else))
>

By applying the same ideas I got my macro to work.

Thanks a lot.

Cheers,

Paulo Matos

> --
>          ((lambda (x) (x x)) (lambda (x) (x x)))          Eli Barzilay:
>                  http://www.barzilay.org/                 Maze is Life!
>



-- 
Paulo Jorge Matos - pocmatos at gmail.com
Webpage: http://www.personal.soton.ac.uk/pocm