On 12/30/2011 04:38 PM, Jerzy Karczmarczuk wrote:
> Bardur Arantsson:
>> Random streams are not referentially transparent, though, AFAICT...?
>>
>> Either way this thread has gone on long enough, let's not prolong it
>> needlessly with this side discussion.
>
> Sure.
> But the discussion on randomness is /per se/ interesting, especially in
> a functional setting.
>
> Anyway, nobody can convince Steve Horne. Perhaps as an "unintentional"
> side-effect...
>
> But random streams, or rather pseudo-random streals (infinite lazy
> lists, as the example I gave, the `iterate` of `next`) are as
> referentially transparent as any Haskell data. Really.
>
Of course -- if you just have a starting seed and the rest of the
sequence is known from there. I was thinking of e.g. those "periodic
re-initialization" ways of doing RNG.
> I *NEVER* used
> "true" random numbers, even to initialize a generator, since in the
> simulation business it is essential that you can repeat the sequence on
> some other platform, with some other parameters, etc.
>
I've heard this a lot from physicists -- of course if you run a
simulation reproducibility can be extremely important (e.g. for
double-checking computations across different machines). However, if
you're doing crypto it may not be so desirable :).
Anyway, I'm out of this thread too :).
Cheers,
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