Re: Instead of pcase

[Po Lu]

Dmitry Gutov <dmitry@gutov.dev> writes:

> OCaml -- maybe not that many. But the sum total of developers writing
> in high-level languages (JavaScript included) is quite high.
>
> Ruby and Python have pattern matching in that style. Rust and Swift do
> too.
>
> JS might be getting one in a few years:
> https://github.com/tc39/proposal-pattern-matching
>
> Java introduced limited/experimental support this year:
> https://openjdk.org/jeps/432
>
> Even the C++ standard might get it one day:
> https://www.stroustrup.com/pattern-matching-November-2014.pdf
> (libraries already available)

That's all well and good, but one of Richard's requests at the outset of
this thread was:

> It's just the opposite for `pcase' -- its specific purpose is a
> low-level purpose, so it could appear in any part of the code of
> Emacs, The burden of its complexity can fall on any or all of us.

> Those of you who are fans of `pcase' may not recognize the cost it
> imposes on the Emacs Lisp language.  You paid that cost already,
> perhaps a few years ago, and perhaps you enjoy each new language
> construct you learn.  Perhaps, for you, the more complexity of
> features to be learned, the better.

> But don't argue that this cost does not exist, simply because it
> doesn't feel like a burden to you.

And thus far this thread has been awash with denials of that burden, one
which unequivocally exists.  This I and others have demonstrated time
and again.

pcase is _not_ fine as-is, however many other languages might provide
analogous constructs.  One man's meat is another man's poison; and it is
up to us to place before either neither his meat nor his poison.