Re: Gearing up (again) for the next release: 2014.2.0.0

Before more people make fun of me, I meant a cryptographic hash function! On Mon, Apr 7, 2014 at 4:32 PM, Johan Tibell wrote:

On Mon, Apr 7, 2014 at 4:18 PM, Nick Smallbone wrote:

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On Monday 07 April, 2014 at 02:53 pm, Johan Tibell wrote:

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Is StdGen so badly broken that it can't be fixed in a future version?

The implementation of split is pretty broken. I suppose most people don't need split but, unfortunately, QuickCheck uses it heavily (the bind of the Gen monad splits the seed). I don't think anyone knows how to fix it, since there's no obvious reason why the current split should work at all!

Basic question: is the type of split wrong or just the implementation?

Just the implementation. However, another question (which I don't know the answer to) is whether the type of StdGen allows for a proper implementation of split.

It would be nice if we could just fix StdGen and thus not require a whole new library. Will fixing StdGen make it even slower than it is today?

I believe the new generator used in QC uses some cartographic hash function. I wonder if SipHash has been considered, as it's both fast and has good randomness properties (but perhaps not for splitting).