Re: Shrinking the C core

[Eric S. Raymond]

Po Lu <luangruo@yahoo.com>:
> "Eric S. Raymond" <esr@thyrsus.com> writes:
> 
> > When I first worked on Emacs code in the 1980s Lisp was already fast
> > enough, and machine speeds have gone up by something like 10^3 since.
> > I plain don't believe the "slower" part can be an issue on modern
> > hardware, not even on tiny SBCs.
> 
> Can you promise the same, if your changes are not restricted to one or
> two functions in fileio.c, but instead pervade throughout C source?

Yes, in fact, I can. Because if by some miracle we were able to
instantly rewrite the entirety of Emacs in Python (which I'm not
advocating, I chose it because it's the slowest of the major modern
scripting languages) basic considerations of clocks per second would
predict it to run a *dead minimum* of two orders of magnitude faster
than the Emacs of, say, 1990.

And 1990 Emacs was already way fast enough for the human eye and
brain, which can't even register interface lag of less than 0.17
seconds (look up the story of Jef Raskin and how he exploited this
psychophysical fact in the design of the Canon Cat sometime; it's very
instructive). The human auditory system can perceive finer timeslices,
down to about 0.02s in skilled musicians, but we're not using elisp
for audio signal processing.

If you take away nothing else from this conversation, at least get it
through your head that "more Lisp might make Emacs too slow" is a
deeply, *deeply* silly idea. It's 2023 and the only ways you can make
a user-facing program slow enough for response lag to be noticeable
are disk latency on spinning rust, network round-trips, or operations
with a superlinear big-O in critical paths.  Mere interpretive overhead
won't do it.

> Finally, you haven't addressed the remainder of the reasons I itemized.

They were too obvious, describing problems that competent software
engineers know how to prevent or hedge against, and you addressed me
as though I were a n00b that just fell off a cabbage truck. My
earliest contributions to Emacs were done so long ago that they
predated the systematic Changelog convention; have you heard the
expression "teaching your grandmother to suck eggs"?  My patience for
that sort of thing is limited.
-- 
                <a href="http://www.catb.org/~esr/";>Eric S. Raymond</a>