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

[Martijn Verburg]

Hi Zheka,

(I'm going to try to reply to everyone since I started this discussion :-))

Whilst I'm not sure about the practically of `final var` in this situation
I can get behind the annotation support, thanks for pointing these out!

Cheers,
Martijn

On 26 January 2018 at 22:59, Zheka Kozlov <orionllmain at gmail.com> wrote:

> The motivation is to allow `final` and annotations on lambda parameters:
>
> (final var x) → x + 1;
> (@Nonnull var x) → x + 1;
>
> This is impossible to write with an implicitly typed lambda:
>
> (final x) → x + 1; // Illegal
> (@Nonnull x) → x + 1; // Illegal
>
>
> 2018-01-26 15:30 GMT+07:00 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
>> >
>>
>
>