Additional method on Stream

[Remi Forax]

On 04/28/2015 03:05 PM, Paul Sandoz wrote:

[...]

>
>> I do understand the desire to control methods, but API design isn't
>> just about minimalism, it is also about meeting common use cases in a
>> natural way. The parallel is of course a standard if (obj instanceof
>> Foo) statement in Java, where developers often curse that they have to
>> additionally cast obj after the check.
> I believe Ceylon might also do contextual type narrowing. I dunno how easy it would to modify the Java language and javac to do similar things. A separate discussion to be had...

I think this was discussed on the coin project mailing list when talking 
about the precise re-throw of exception.
The main issue is that a more precise type will select another overload 
than the one that javac currently select:

class A {}
class B extends A {}
class Bar {
   void foo(A a) { ... }
   void foo(B b) { ... }
}

Let suppose we have this code:
   A a = ...
   if (a instanceof B) {
     foo(a);
   }

without narrowing, it will call foo(A), with narrowing, it will call foo(B).

Rémi