Re: Replace trivial pcase occurrences in the Emacs sources

[Dmitry Gutov]

On 31.10.2018 22:03, Stefan Monnier wrote:
> > A thing can be called "destructuring" if it destructures something.
> > It's like a "flying carpet": the carpet that flies.  But in our case
> > the patterns don't destructure anything, they are a means for
> > destructuring.
>
> And let's not forget that what I used this term currently is to talk
> about the specific way pcase patterns are used within pcase-let
> (i.e. the way pcase-let and friends skip the tests to verify that the
> pattern does match).

That part of the explanation is pretty counter-intuitive to me. I mean, 
I get what it's saying (pcase-let skips certain checks), but that's not 
a property of a pattern (which is a certain form), so the phrase 
"destructuring pattern" (which, in my mind, should just describe the 
pattern) shouldn't imply a particular aspect of its use.

The way I think of the situation is pcase performs both the structure 
check and destructuring, and pcase-let only performs destructuring. But 
destructuring is present in both cases and it's a property of the 
pattern (and maybe of the input data if the pattern includes an "(or").

> So maybe we should just say "a pattern used to destructure" to clarify
> that it's not a property of the pattern but of the way it's being used.

Maybe we shouldn't try to explain that through saying that patterns 
exhibit a certain property in this situation, and explain that purely in 
terms of behavior of certain macros (pcase-let and pcase-dolist, IIRC)?