Gearing up (again) for the next release: 2014.2.0.0

Nick Smallbone nicsma at chalmers.se
Mon Apr 7 12:25:28 UTC 2014


harry <voldermort at hotmail.com> writes:
> Nick Smallbone-2 wrote
>> I would rather not switch back to StdGen. We have stumbled into
>> situations in the past where we can't falsify a property just because
>> StdGen can't come up with the right random values - while (thankfully)
>> extremely rare, it makes me uncomfortable that it happens at all.
>> This mostly happens when generating random functions.
>
> 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!

Nick


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