Re: Instead of pcase

[Richard Stallman <rms@gnu.org>]

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My aim in cond* is to include the convenient aspects of pcase without
its rigidity of framework, which requires the programmer to squeeze
things into it that don't easily fit.  That rigidity is the fact that
if you want to put one clause into a pcase which can't be written in
pcase language, you have to redesign that whole pcase.

I suspect that that rigidity creates pressure to extend pcase language
to be universal -- so that there can't ever be one clause that you
"can't express in pcase language."

cond* avoids that problem completely.  It lets you use pcase-like
patterns where they are convenient, interspersed with Lisp code where
that is convenient.

The cond* pattern specification is a little more complex than it was
in the first version, but it is still far simpler than the pcase
language.

As far as I know, it needs no further extension.  I looked at the 
pcase examples that were suggested, and they don't need any further
extension.

The `cdr' and `cdr-safe' feature is not strictly necessary, but the
lack of this feature in pcase leads to filling up many patterns with
lots of `_' subpatterns.  I think this feature is an improvement, but
omitting it would only reintroduce the added complexity of those `_'
subpatterns.

Can anyone show me more pcase examples I should study, which you think
show cases that call for adding any more pattern features to cond*?

-- 
Dr Richard Stallman (https://stallman.org)
Chief GNUisance of the GNU Project (https://gnu.org)
Founder, Free Software Foundation (https://fsf.org)
Internet Hall-of-Famer (https://internethalloffame.org)