Feedback wanted: switch expression typing

[forax at univ-mlv.fr]

The fact that the semantics of ?: is very ad-hoc is a kind of accident of the history,
we may want to fix it but i do not see why we have to fix it at the same time that we introduce the expression switch,
we can fix the semantics of ?: later or never.

Rémi

----- Mail original -----
> De: "daniel smith" <daniel.smith at oracle.com>
> À: "Remi Forax" <forax at univ-mlv.fr>
> Cc: "amber-spec-experts" <amber-spec-experts at openjdk.java.net>
> Envoyé: Samedi 31 Mars 2018 03:44:49
> Objet: Re: Feedback wanted: switch expression typing

>> On Mar 30, 2018, at 10:54 AM, Remi Forax <forax at univ-mlv.fr> wrote:
>> 
>> I do not see (B) as sacrifying the consistency because the premise is that an
>> expression switch should be consistent with ?:
>> 
>> But an expression switch can also be modeled as a classical switch that returns
>> it's value to a local variable.
>> 
>>  int a = switch(foo) {
>>    case 'a' -> 2;
>>    case 'b' -> 3;
>>  }
>> can be see as
>>  int a = $switch(foo);
>> with
>>  int $switch(char foo) {
>>    case 'a': return 2;
>>    case 'b': return 3;
>>  }
> 
> I mean, sure, this is another way to assert "switches in assignment contexts
> should always be poly expressions".
> 
> But it's just as easy to assert "conditional expressions in assignment contexts
> should always be poly expressions".
> 
> int a = test ? 2 : 3;
> can be seen as
> int a = $conditional(test);
> with
> int $conditional(boolean test) {
>    if (test) return 2;
>    else return 3;
> }
> 
> Those are probably good principles. But if we embrace them, we're doing (C).
> 
> —Dan