JEP proposed to target JDK 11: 323: Local-Variable Syntax for Lambda Parameters

[Martijn Verburg]

I'd be interested in some empirical numbers around the usage in Groovy of
the two styles of declaration!

I'm also trying hard not to get caught up only thinking about syntax here.
I know that I'm someone who's not a qualified language or VM expert and
that I've more than likely got caught up thinking about the wrong problem
(syntax vs semantics).





Cheers,
Martijn

On 26 January 2018 at 21:38, Cédric Champeau <cedric.champeau at gmail.com>
wrote:

> Hi Martijn,
>
> I share your thoughts. I understand the will to streamline the use of
> "var". However, since
>
> (var x, var y) -> x+y
>
> is strictly equivalent to:
>
> (x,y) -> x+y
>
> I'm not sure I see the advantage of this. From my experience with Groovy,
> where both are supported ( { def x, def y -> ) and ( { x,y ->), I think
> most people stick with the short syntax, the longer one seems to imply
> different semantics (why use a different syntax if its the same ?), where
> there are not.
>
> 2018-01-26 9:30 GMT+01:00 Martijn Verburg <martijnverburg at gmail.com>:
>
> > Hi all,
> >
> > I'm struggling to understand the motivation for this JEP in terms of it
> > adding improved understanding or readability of source code (as the
> > implicit case is already covered today).
> >
> > I also suspect the illegal use uses (extract below) will likely confuse
> and
> > frustrate day to day developer's who don't understand the underlying type
> > inference system and lead to
> > some heavily upvoted SO Q's.  I liken this type of frustration seen in
> > developers not understanding generics in full and coming undone in corner
> > cases where they expect the element of
> > 'least surprise'.
> >
> > ------
> >
> > The following examples are illegal:
> >
> > (var x, y) -> x + y        // Cannot mix var and "no var" in
> > implicitly typed lambda expression
> > (var x, int y) -> x + y    // Cannot mix var and manifest types in
> > explicitly typed lambda expression
> >
> >
> > -------
> >
> > I'm not sure I've explained myself very eloquently here, hope this has
> made
> > some sense.
> >
> > Cheers,
> > Martijn
> >
> > On 26 January 2018 at 08:40, <mark.reinhold at oracle.com> wrote:
> >
> > > The following JEP is proposed to target JDK 11:
> > >
> > >   323: Local-Variable Syntax for Lambda Parameters
> > >        http://openjdk.java.net/jeps/323
> > >
> > > Feedback on this proposal is more than welcome, as are reasoned
> > > objections.  If no such objections are raised by 23:00 UTC on Thursday,
> > > 1 February, or if they're raised and then satisfactorily answered, then
> > > per the JEP 2.0 process proposal [1] I'll target this JEP to JDK 11.
> > >
> > > - Mark
> > >
> > >
> > > [1] http://cr.openjdk.java.net/~mr/jep/jep-2.0-02.html
> > >
> >
>