On 11/23/2016 05:47 AM, Joseph Rushton Wakeling wrote:
On Wednesday, 23 November 2016 at 01:34:23 UTC, Andrei Alexandrescu wrote:
I'm unclear on what that statistically unsafe default behavior is - my
understanding is it has to do with RNGs being inadvertently copied. It
would be great to formalize that in a well-explained issue.
I'll see if I can write that up in depth some time soon. TBH though I
think the problem is less about RNGs and more about stuff like
RandomSample and RandomCover (and, in future, random distributions that
have internal state, like a struct implementing a normal distribution
using the Ziggurat algorithm internally).
It's not so difficult to stop RNG state being copied inadvertently, but
when you have ranges wrapping ranges wrapping ranges, each containing
their own extra state that cannot be copied by value, things get a bit
more complicated.
Well we need to get to the bottom of this if we're to make progress.
Otherwise it's copypasta with little changes followed by disappointment
all the way down. -- Andrei
