[plt-scheme] Macro-expansion-time structs

Would (begin-for-syntax (define-struct etc ())) not work as well?
Jos

----- Original Message ----- 
From: "Carl Eastlund" <cce at ccs.neu.edu>
To: "Henk Boom" <lunarc.lists at gmail.com>
Cc: "Eli Barzilay" <eli at barzilay.org>; <plt-scheme at list.cs.brown.edu>
Sent: Sunday, October 12, 2008 6:37 AM
Subject: Re: [plt-scheme] Macro-expansion-time structs


> If you want the my-box struct bound at the module level, you can
> create another module, use define-struct normally, then import it for
> syntax.  Or you can use define-values-for-syntax like this (which
> won't get the struct's syntax binding, but will get anything else you
> need):
>
> #lang scheme/base
>
> (require (for-syntax scheme/base))
>
> (provide test)
>
> (define-values-for-syntax (make-my-box my-box-val my-box?)
> (let ()
>   (define-struct my-box (val))
>   (values make-my-box my-box-val my-box?)))
>
> (define-syntax test
>  (lambda (stx)
>    #`#,(my-box-val (make-my-box 2))))
>
> On Sat, Oct 11, 2008 at 11:22 PM, Henk Boom <lunarc.lists at gmail.com> 
> wrote:
>> 2008/10/11 Carl Eastlund <cce at ccs.neu.edu>:
>>> You've defined the struct in the runtime environment.  You need to
>>> define it in the transformer environment if you want transformers to
>>> use it.  You might accomplish that like this (though this makes a
>>> local definition other transformers won't be able to use):
>>>
>>> #lang scheme/base
>>>
>>> (require (for-syntax scheme/base))
>>>
>>> (provide test)
>>>
>>> (define-syntax test
>>>  (let ()
>>>   (define-struct my-box (val))
>>>   (lambda (stx)
>>>     #`#,(my-box-val (make-my-box 2)))))
>>
>> I see. It's a pity that (begin-for-syntax (define-struct . . .)) doesn't 
>> work.
>>
>> Thanks for the info!
>>    Henk
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