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Re: syntax-local-binding

From: Andy Wingo
Subject: Re: syntax-local-binding
Date: Fri, 20 Jan 2012 22:23:04 +0100
User-agent: Gnus/5.13 (Gnus v5.13) Emacs/23.3 (gnu/linux)

On Fri 20 Jan 2012 21:26, Mark H Weaver <address@hidden> writes:

> Andy Wingo <address@hidden> writes:
>>     `lexical'
>>           A lexically-bound variable.  The value is a unique token (in
>>           the sense of `eq?') identifying this binding.
>>     `macro'
>>           A syntax transformer, either local or global.  The value is
>>           the transformer procedure.
> Ironically, `syntax-local-binding' renders the current simple
> implementation strategy of `the-environment' inadequate, because
> identifier-syntax is no longer sufficient to simulate a lexical.

Why do you say that?

> In particular, I was hoping to change the binding representation of
> `syntax-rules' macros so that they are serializable.  In particular,
> they would be represented by the `syntax-rules' form itself (the same
> one that psyntax currently passes to `primitive-eval' to produce the
> transformer procedure).  A weak-key hash table would cache the compiled
> transformer procedures.
> This would allow (the-environment) to capture locally-bound
> `syntax-rules' macros.  Unfortunately, `syntax-local-binding', as
> currently documented, now makes this impossible.

Why do you think that?  The procedures do carry metadata; I understood
that that was your strategy, to use the serialization of the
syntax-rules form in the procedure metadata.


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