Re: Update of pcase docs for the elisp manual

[Eli Zaretskii <eliz@gnu.org>]

> From: John Wiegley <jwiegley@gmail.com>
> Cc: Michael Heerdegen <michael_heerdegen@web.de>,  emacs-devel@gnu.org
> Date: Tue, 26 Jan 2016 08:59:42 -0800
> 
>   - Is there any way we can get rid of the phrases QPattern and UPattern?
>     There's decades of prior literature on pattern matching in functional
>     languages, and none of them use "QPattern" and "UPattern". We're inventing
>     terms that make no sense at all to newcomers, except for the single-letter
>     correspondence with "quoted" and "unquoted". What if we just call them
>     "quoted patterns" and "unquoted patterns", if that is what we mean?

The alternatives you propose are longer, which makes it harder to
produce palatable descriptions.  And there's a long tradition of using
them in Emacs.

But I don't own the manual; if you want to get rid of those terms, go
ahead and make the change.

>     I still vote for "literal" and "logical", since a literal pattern matches
>     by literally being the same value as the input, while a logical pattern
>     matches due to the logic of the pattern.

AFAIU, your division into logical and literal was different from the
division between UPatterns and QPatterns.  That's why I didn't use
those terms.

>   - The docs say "UPatterns are simpler, so we describe them first." Don't
>     UPatterns represent the entire complexity of `pcase'?

On the implementation level, yes.  But that's not really relevant for
the documentation (except that we really should say so and give an
example).

>     How are they simpler?

They are to me.  They use undecorated symbols, and don't require the
quote/unquote games.  If that doesn't explain why they are simpler,
then I don't know how to explain it, but the gut feeling is very real.