Re: Emacs Lisp's future

[Stefan Monnier]

> I've been going through some 10 year old elisp of mine recently.
> The thing that surprises me is how many times I mention performance in
> it.  I rarely worry about this these days.  Elisp performance as is
> seems rarely an issue.

I think this reflects 2 things:
- machines still did get faster over the last 10 years (much less so
  than over the preceding 10 years, but also probably much more so than
  over the next 10 years).
- you've internalized Elisp performance sufficiently that you
  self-censor yourself such that you don't bump into it.

> Where I would say that there is an issue is that too much of Emacs is
> written in C.  Having a faster elisp would allow moving more into lisp
> and thus having more of Emacs extensible dynamically.

That's part of the idea, yes.

> I'd add a fourth. People who want to extend Emacs for their own purposes
> have to learn it.  Having JS extensibility would be an enourmous win.

I'm far from convinced.  It may seem that way if you don't think too
hard about what it would look like, but once you realize that your JS
hacker will have to learn how to manipulate Elisp lists, Elisp vectors,
Elisp symbols, how to access Elisp functions and Elisp variables ...

That JS code won't look very much like your typical JS code.  It will be
so baroque that they will "have to learn it".  And they may even hate it
more (because it surely will look ugly).

Interoperability between languages is *hard*.  Doing it so the result is
lightweight and elegant (and moderately efficient) is rarely possible.


        Stefan