I find these arguments not-remotely-compelling. Variable declarations
should look like declarations; it is highly error-prone to have the mere
mention of a name cause it to spring into being. I see no value, and
much anti-value, in having `Point(x)` introduce a new variable x.
So, no. I think that would be a very bad idea.
On 9/13/2020 3:10 PM, fo...@univ-mlv.fr wrote:
------------------------------------------------------------------------
*De: *"Brian Goetz" <brian.go...@oracle.com>
*À: *"Remi Forax" <fo...@univ-mlv.fr>
*Cc: *"amber-spec-experts" <amber-spec-experts@openjdk.java.net>
*Envoyé: *Dimanche 13 Septembre 2020 20:34:54
*Objet: *Re: Updated patterns-in-switch doc
I don’t quite get the leap from “no constant patterns” to
changing the syntax of deconstruction patterns, but in any
case, we definitely don’t want this (and in fact, for the
same reasons cited in the section on constant patterns,
and others.)
if case Point(x, y) can not mean instanceof Point p where p.x
== x && p.y == y, then case Point(x, y) can have the same
meaning has a lambda (x, y), introducing two fresh variables x
and y.
If you're making the claim that "It would not be disastrously
inconsistent for it to work that way", I agree. But I think it
would still be quite foolish of us to go that way anyway. The
benefit is tiny (a few fewer characters typed) at a very
considerable cost -- reduced readability, and potential ambiguities.
The main issue i see with using var is that when you have nested
patterns, "var" starts to becomes noise because you start to have
several of them, so it makes the nesting less obvious.
For me, var is good the first times to see how pattern matching works,
it's very similar how as a beginner you are prefixing everything with
"this" but after some times, it falls into the noise category,
that why i'm not proposing to not allow "var" but to allow to not use
"var".
Again, this is very similar to the things we were discussing during
the conception of lambdas, should we try to protect them with a lot of
syntax to say, this is the new thing or should we try to make the
syntax simpler with the risk of people not understanding it.
Rémi
