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Re: [PATCH] Implement `the-environment' and `local-eval' in evaluator

From: Andy Wingo
Subject: Re: [PATCH] Implement `the-environment' and `local-eval' in evaluator
Date: Sat, 07 Jan 2012 02:26:27 +0100
User-agent: Gnus/5.13 (Gnus v5.13) Emacs/23.3 (gnu/linux)

On Fri 16 Dec 2011 20:12, Mark H Weaver <address@hidden> writes:

> So, in cases where (the-environment) is found within a macro template,
> I guess I'm still undecided about whether the captured expander
> environment should be at the point of (the-environment), or whether it
> should be at the point of the initial macro use that led to that
> expansion.

Here's the thing, I think: FOO and (local-eval FOO (the-environment))
should be equivalent.  These two are the same:

  (library (a)
    (export fetch-a)
    (import (guile))
    (define a 42)
    (define-syntax fetch-a
      (syntax-rules () ((_) a))))

  (library (a)
    (export fetch-a)
    (import (guile))
    (define a 42)
    (define-syntax fetch-a
      (syntax-rules () ((_) (local-eval 'a (the-environment))))))

So I think that the environment should be captured such that these
semantics are followed.  I think that means the former, of your two


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