Re: Emacs Lisp and Guile

[Marius Vollmer <mvo@zagadka.ping.de>]

Richard Stallman <rms@gnu.org> writes:

>     All Elisp variables would be constructed specially, even if they
>     didn't make use of any of the available features initially.  That
>     would mean that variables declared in Scheme can not be later made
>     buffer local since normal Scheme variabled would not be constructed in
>     the special way.
> 
> This would be a big inconvenience in practice.  It would mean that
> mentioning a variable in Scheme code once prevents you from using it
> in other ways.  It needs to be possible to make a variable "special"
> (in this sense) after having used it in other non-lexical ways.

Hmm, I think that maybe Scheme people will prefer to explicitely
declare that a variable is buffer local at the point of its
definition.  But maybe I'm wrong.

In any case, we can reverse the logic and say that variables need to
be specially constructed when the user does not want them to be used
"specially" (i.e., buffer-locally, etc).

That would work just as well, I think.

Variables that hold functions would be a candidate, for example.  That is,

  (define foo #f)

would construct a normal variable that can be made thread-local,
buffer-local, etc., while

  (define (frob-foo)
    ...)

would construct a 'dumb' variable that can't these things, but that
would allow faster access.

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