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Re: problems with syntax-case and with-syntax
From: |
Matt Wette |
Subject: |
Re: problems with syntax-case and with-syntax |
Date: |
Mon, 18 Sep 2017 06:16:51 -0700 |
> On Aug 27, 2017, at 6:35 PM, Mark H Weaver <address@hidden> wrote:
>
> Mark H Weaver <address@hidden> writes:
>
>> The problem is that in Guile 2.2, whenever (define <id> ...) is found in
>> the expanded code, where <id> was introduced by a macro (i.e. not passed
>> as an explicit argument to the macro), Guile will rewrite the <id> into
>> a new name based on the hash of the entire definition form.
>
> I forgot to mention that only top-level definitions are munged in this
> way.
>
> Also, my parenthetical definition of what it means to be "introduced by
> a macro" lacked precision. To avoid <id> being "introduced by a macro",
> it's not enough for <id> to have been passed an argument to the macro
> that generated the definition. If that were the case, you could work
> around this by adding an additional layer of macros, where the upper
> layer generated <id> and passed it down to the lower layer which would
> generate the definition.
>
> To avoid <id> being considered "introduced by a macro", <id> must
> ultimately occur verbatim in the source code outside of any macro
> template.
I have read through the posts, and the Guile 2.2 ref manual. The explanations
are not quite complete in my mind. If all top-level id's introduced by macros
were munged, then it would break a lot of existing code. See, for example,
the `define-structure' example in "The Scheme Programming Language", 4th ed.
It seems identifiers introduced by datum->syntax are preserved, as long
as they are not redefined. Is that correct?
In my case, I was redefining by architecture (or convention). I was generating
"wrap-" + <identifier> in a macro that called a another macro that made the
same
definition. Is it bad form to assume an convention like this?
Off to do more reading on this: Dybvig's paper on syntax-case and I have the
book too. and R6RS ...
Matt
- Re: problems with syntax-case and with-syntax,
Matt Wette <=