Serialization opt-in syntax (again)

Kevin Bourrillion kevinb at
Mon Oct 8 09:24:46 PDT 2012

I'm sorry that I'd forgotten this _ suggestion before. I like it.

On Mon, Oct 8, 2012 at 9:20 AM, Brian Goetz <brian.goetz at> wrote:

> still evaluate whether it's worth offering the (& Serializable)
>> shorthand as well.  The shorthand has benefits similar to the Java 7
>> "diamond", though I must concede the situation only comes up a tiny
>> fraction as often.
> I agree that it is worth considering such.  But, my preference here would
> be to deal with this and other sorts of verbosity in a single more
> coordinated stroke, rather than ad-hoc shorthands.  For example, at the EG
> meeting we talked about reclaiming _ as a syntactic token.  One of the
> motivations for having an "I don't want to say" token would be to support
> partial type inference.  For example, we currently support diamond as
> all-or-nothing, but something finer-grained could fit right into our
> existing machinery if it had a syntax:
>   new Foo<String, _>(...)           // partial diamond
> Similarly, we support inferring lambda type parameters as all-or-nothing,
> but given a syntax, could do something finer-grained:
>   (String s, _ y) -> ...            // partial implicit lambda
> And for target-typed lambdas, we could let inference fill in what is known
> about the target type:
>   (_ & Serializable) e -> true
> I think a more coordinated attack (in the future) on redundant type
> declarations would be a better choice than creating ad-hoc shorthands in
> specific situations.  (Obviously we'd have to have a long discussion on the
> actual syntax.)

Kevin Bourrillion | Java Librarian | Google, Inc. | kevinb at
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