Nullable switch

[forax at univ-mlv.fr]

I've re-read the proposed spec about the nullable switch, 
and it still don't understand why people will think that that the following switch is a nullable switch 
switch(o) { 
case String s -> 
case Object o -> 
} 

The current spec merges the notion of totality and of nullability and i fail to understand why. 

Moreover, the spec explain that we need a any pattern but don't explain why having an explicit syntax "any foo", which separate the notion of totality and nullability is not a good idea. 

i wonder what is the problem of introducing a syntax "any foo" explicitly. 

with the following rules for a nullable switch: 

    * A switch with a constant null case will accept nulls; 
    * If present, a constant null case must go first; 
    * A switch with an any case matches also accepts nulls; 
    * If present, an any case must go last. 

By example, 
Object o = ... 
switch(o) { 
case var o -> // non null Object 
case any o -> // nullable Object 
} 

In that case, the following switch is not nullable 
switch(o) { 
case String s -> 
case Object o -> 
} 

and the nullable version is 
switch(o) { 
case String s -> 
case any o -> 
} 

regards, 
Rémi 

> De: "John Rose" <john.r.rose at oracle.com>
> À: "Remi Forax" <forax at univ-mlv.fr>
> Cc: "Brian Goetz" <brian.goetz at oracle.com>, "amber-spec-experts"
> <amber-spec-experts at openjdk.java.net>
> Envoyé: Vendredi 24 Juillet 2020 03:20:20
> Objet: Re: Next up for patterns: type patterns in switch

> On Jul 23, 2020, at 2:53 PM, Remi Forax < [ mailto:forax at univ-mlv.fr |
> forax at univ-mlv.fr ] > wrote:

>> var x and default are not on the same plane. So it's not really a third thing.
>> We are introducing something special for the bottom, null, but not for the top ?

> Eh; null doesn’t need to be that special, but Brian’s point is that
> you can just mandate that it appears at the top or nowhere.
> If you don’t mandate that, then type-coverage checks ensure
> that a “case null” which appears after a nullable case (a total
> one) will be not-reachable, and a static error.
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