Re: tail call reduction

[Miles Bader <miles@gnu.org>]

Oliver Scholz <alkibiades@gmx.de> writes:
>>> I recommend you check out the lexbind branch which introduces
>>> static scoping
>>
>> For those who aren't users of the cvs and other such programs,
>> where do you get this lexbind emacs-version?
>
> Unless I am mistaken (and somebody packaged it and put it on the web
> somewhere) you can get it only with cvs or "other such programs" (such
> as GNU arch). With cvs you can use the option "-r lexbind" to check
> out the lexbind branch.

Yes as far as I know it's only available via CVS (as you say, the
"lexbind" tag, using something like "cvs co -r lexbind emacs") or GNU
arch (my `miles@gnu.org--gnu-2005/emacs--lexbind--0' branch).

BTW, it's quite usable as your normal emacs (I use it), i.e., it doesn't
crash a lot or anything.  However, it's really no different in behavior
from stock Emacs unless you explicitly mark certain source files as
"lexically bound" -- and then it's more for someone interested in
hacking on the byte compiler than for production use.

Basically, the status of the lexbind branch is this:

 * Lexical binding should work properly in interpreted lisp code.

 * The runtime support for lexically-bound compiled code should work
   fine (it's not particularly complicated).

 * HOWEVER, the byte-compiler fails to compile certain types of code
   properly when using "lexically-bound" mode.

   It should compile straight-forward code properly (e.g. normal
   variables just used within a function), but incorrectly handles many
   cases where it must pass explicit lexical environments around (e.g.,
   where a lambda expression uses a lexically bound variable from the
   surrounding environment).  [Much of the compiler support for this is
   written, just not debugged and made to work.]

If you are interested in the issue, however, I'd certainly appreciate
some help... :-)  I haven't actively worked on it for a while, but
I keep the branch up-to-date, and make sure the code doesn't bit-rot.

-Miles
-- 
If you can't beat them, arrange to have them beaten.  [George Carlin]