Re: Syntax-Case macro that selects the N-th element from a list

[Dr. Arne Babenhauserheide]

Hi Linus,

thank you for your tipps!

Linus Björnstam writes:

> Can you use the procedural part of syntax-rules? You have the power of 
> using scheme at expansion time, which means you could do list-ref all 
> you want.
> 
> That "syntax-rules" is of course syntax-case.
> 
> The only thing is that guile lacks syntax->list, so sometimes you have 
> to manually turn it into a list. Say you are matching ((_ stuff ...) 
> Body) stuff is a syntax object. You could turn it into a list of syntax 
> objects by doing  #'(stuff ...). Then you can treat it as a regular 
> list, and use quasisyntax to put it back into your output syntax. 
…
> Try writing it first with unhygienic macros and get that working
> before porting to syntax-case if you don't know the ins-and-outs of
> syntax-case.

I have not yet written an unhygienic macro in Guile.

Do I use the internal macros for that?

Best wishes,
Arne
-- 
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