Re: pending branch: lexical-literals

[Andy Wingo <wingo@pobox.com>]

On Fri 06 May 2011 14:17, ludo@gnu.org (Ludovic Courtès) writes:

> Sorry for the late reply.

No prob; thanks for thinking through it!

> So, with this change, no top-level binding of ‘else’ is /required/, but
> /when/ there is one, it prevails over the literal, correct?

Sorta?  This language is imprecise.  The real language is in R6RS: 

    The free-identifier=? procedure returns #t if and only if the two
    identifiers would resolve to the same binding if both were to appear
    in the output of a transformer outside of any bindings inserted by
    the transformer. (If neither of two like-named identifiers resolves
    to a binding, i.e., both are unbound, they are considered to resolve
    to the same binding.)

Nothing changes in the case that `else' is unbound always.

The change is if it is bound when the macro is defined, but not when it
is used, or vice versa; or, also, if it is bound at both places, but to
different lexical or toplevel variables.  In these cases the
lexical-literals branch causes the literals not to match.

OTOH currently a keyword imported under a different name will not match
itself; this branch allows renaming keywords.

> But then I don’t understand how the story that you could import/rename
> ‘else’ fits into this.

I guess basically the summary is "compare literals by identity, not by
name".

Andy
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