Re: Trouble trying to understand how low level macros interact with module system.

What's probably happening here is a bad interaction between the module
system and the low-level macro macro.  define-macro is defined in
terms of define-syntax.  One of the things that a define-syntax macro
does that a define-macro does not is manage the references to other
definitions needed during the macro transformation.

The (module ((some-macro some-binding))... form instructs the module
system that the macro needs that binding to operate.  In the case of
define-macro though, I don't believe the reference to thefunc is
rewritten to refer to the binding *inside the module*.  define-macro
is pretty simple in that respect, and just spits out an s-expression
based on your definition, with little or no rewriting.



On Sun, Nov 30, 2008 at 6:44 AM, Igor Hjelmstrom Vinhas Ribeiro
<[email protected]> wrote:
> Hello, Mike - thanks for the reply!
>
>    Unfortunately, however, this also doesn't work[1]:
>
>    Any other clue on what could be wrong?
>
> Regards,
>  Igor.
>
> [1]. See below - trying Mike's suggestion. As before, calls to
> amacro fail stating that thefunc is undefined, while direct calls
> to thefunc work just fine.
>
> SISC (1.16.6)
> #;> (max-stack-trace-depth 16)
> 0
> #;>
> #;> (amacro)
> Error: undefined variable 'thefunc'.
> ---------------------------
> Some stack trace entries may have been suppressed. To see all entries set
> the dynamic parameter suppressed-stack-trace-source-kinds to '().
> #;> (thefunc)
>
>
> ---
>
> #;>
>
> On Sat, Nov 29, 2008 at 23:53, Mike J. Bell <[email protected]> wrote:
>>
>> Try:
>>
>> (module ((thefunc) (amacro thefunc))
>>   (define-macro amacro (lambda () (thefunc)))
>>   (define (thefunc) (display "\n\n---\n\n")))
>>
>> This (I think) means make an anonymous module with two exported symbols,
>> thefunc and amacro (which depends on thefunc).
>>
>> Somebody else can I'm sure give you a better theoretical reason why this
>> works (and what it really means, and why yours does what it does, which
>> isn't very intuitive to me off hand).
>>
>> Mike
>>
>>
>> On Sat, Nov 29, 2008 at 8:02 PM, Igor Hjelmstrom Vinhas Ribeiro
>> <[email protected]> wrote:
>>>
>>> Hello!
>>>
>>>    I am trying to understand how the module system used by SISC
>>> interacts with the low-level macros that SISC supports.
>>>
>>>   Specifically, I am trying to figure out why the follow snippet of
>>>   code, an anonymous module that exports amacro and thefunc,
>>>   doesn't work.
>>>
>>>    (module (amacro thefunc)
>>>      (define-macro amacro (lambda () (thefunc)))
>>>      (define (thefunc) (display "\n\n===\n\n")))
>>>
>>>   After I pasted it in the REPL, when I call (amacro) I get:
>>>
>>>    #;> (amacro)
>>>    Error: undefined variable 'thefunc'.
>>>    console:16:7: <indeterminate call>
>>>
>>>   Curiously, if I just go ahead and type (thefunc) it works:
>>>
>>>    #;> (thefunc)
>>>
>>>
>>>    ===
>>>
>>>    #;>
>>>
>>>    Is anyone able to explain to me why this happens?
>>>
>>> Regards,
>>>  Igor.
>>>
>>> -------------------------------------------------------------------------
>>> This SF.Net email is sponsored by the Moblin Your Move Developer's
>>> challenge
>>> Build the coolest Linux based applications with Moblin SDK & win great
>>> prizes
>>> Grand prize is a trip for two to an Open Source event anywhere in the
>>> world
>>> http://moblin-contest.org/redirect.php?banner_id=100&url=/
>>> _______________________________________________
>>> Sisc-users mailing list
>>> [email protected]
>>> https://lists.sourceforge.net/lists/listinfo/sisc-users
>>>
>>
>>
>>
>> --
>> Mike J. Bell on gmail
>
>
> -------------------------------------------------------------------------
> This SF.Net email is sponsored by the Moblin Your Move Developer's challenge
> Build the coolest Linux based applications with Moblin SDK & win great
> prizes
> Grand prize is a trip for two to an Open Source event anywhere in the world
> http://moblin-contest.org/redirect.php?banner_id=100&url=/
> _______________________________________________
> Sisc-users mailing list
> [email protected]
> https://lists.sourceforge.net/lists/listinfo/sisc-users
>
>

-------------------------------------------------------------------------
This SF.Net email is sponsored by the Moblin Your Move Developer's challenge
Build the coolest Linux based applications with Moblin SDK & win great prizes
Grand prize is a trip for two to an Open Source event anywhere in the world
http://moblin-contest.org/redirect.php?banner_id=100&url=/