Re: Project Valhalla – Value Types slides from ScalaDays Amsterdam 2015

Brian Goetz brian.goetz at
Fri Jun 12 08:47:58 UTC 2015

Very nice.  

A few comments:

#11: object headers are typically 2 words; a klass pointer and a word for various identity support (GC mark bits, locking, etc.) Which makes the density story with small objects even worse.  

In general, values give us both DENSITY (memory efficiency) and FLATNESS (cache efficiency.)  

#36: in addition to the __ByValue obviously being a syntax placeholder, the restrictions outlined e.g. in #38 (must say final) will also go away — we’re just not focusing at all on syntax for the time being.  

#39: equality on value types will work as it does on primitives (as you suggest on #88)

#121: good summary

On Jun 12, 2015, at 8:57 AM, Simon Ochsenreither <simon at> wrote:

> Hey everone!
> If you are interested, here are the slides I used in my talk at ScalaDays
> Amsterdam:
> I hope the slides gave a correct description of the current situation...
> Thanks!
> Bye,
> Simon

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