Can we also get some feedback on specialization, please?

Martijn Verburg martijnverburg at
Mon Jan 5 19:58:52 UTC 2015

Hi Brian/Valhalla members,

Thanks for this timely post! I've been lurking on this list for some time
wondering how best we (Adoption Group / Java User Groups) can assist. The
best course so far has been to do nothing as our membership typically don't
have the expertise to contribute at this early stage, except for cheer
leading. On that note, the community at large is very excited (the volume
of well meaning blog posts and conf talks etc attest to this) about seeing
Value Type/Packed Objects/Whatever the end result will be - so thanks to
everyone here for tackling this beast, we kinda thought at one stage it
would never get looked at!

Sounds like there might be a couple of things we could do now? So here's my
suggestions (please push back if this is not helpful / too early):

1.) We have an OpenJDK hack day on the 17th of Jan. I could write up a
quick "How to build Valhalla and write some code against it" guide and send
it here for review/upload to the project site. We could have some of the
more advanced members of the LJC in give specialisation a go (assuming they
understand it, but IIRC some of them lurk on this list and are quite
capable).  Typically for speed on the day we have a small GitHub based
project/tutorial to collate code samples that people try (as we did for
Lambdas and Date & Time), maybe that could serve as a point for other more
advanced members in the community to try their hands at.

2.) Provide more resources on the Valhalla project page and a guide on how
to contribute at levels X, Y and Z which would roughly correspond to (X)
Full time - JVM internal expert/implementers, (Y) Advanced Java/JVM users
(e.g. Popular framework/lib authors and such like) and (Z) Joe/Jane Java
Application Devs who are excited to try things as early as is deemed

Let me know if either of those two are helpful and if the Valhalla project
wants us to do anything else (e.g. We can also work on promotion and
dissemination of the hopefully *correct* information).


On 5 January 2015 at 19:35, Brian Goetz <brian.goetz at> wrote:

> There's been a lot of passionate discussion here about the directions we
> should or should not take Java. And this is all understandable, and perhaps
> inevitable, but ... it seems to be crowding out what is actually the
> primary purpose of this (-dev) list.  We had hoped, in taking the effort to
> write up State of the Specialization, to get some comments on ...
> specialization :)
> So far, nearly all the comments have been on the speculative parts of the
> writeup (layers/conditional methods), as well as the usual (supersized)
> portion of "I think you should do X/Y/Z instead".  Which is all OK, but we
> were actually hoping to get some feedback on the part that is written up in
> some detail -- and mostly implemented!  I know it's fun to discuss the big
> sexy stuff, but we can't let this crowd out the main goal.
> So my question is: has anyone tried to write a program with specialized
> generics with the valhalla implementation?   Well, we'd really appreciate
> it.
> I know people want to contribute.  At least right now, here's what
> contribution looks like from our perspective:
>    1.) Please try it out!  Write some code!
>    2.) Tell us what works and what doesn't!
>    3.) Nice comments are always a bonus!  (And are welcome even if you
> didn't do (1) and (2)).
>    4.) If you can't do (1) and (2), and still have something important to
> say in the big-picture department, please do it a) nicely, b)
> constructively, c) succinctly.
> Thanks,
> -Brian

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