[Haskell-cafe] Monte Carlo Pi calculation (newbie learnings)

Jonathan Cast jonathanccast at fastmail.fm
Tue Nov 6 22:15:47 EST 2007

On 6 Nov 2007, at 3:56 PM, Yitzchak Gale wrote:

> I wrote:
>>> There is still a problem here - my code (and also
>>> all of the previous posters, I think) clobbers the random
>>> generator, rendering it unusable for future calculations.
>>> In this case that is probably not a problem, but it
>>> is a bad habit to get into, and not very polite.
> Jonathan Cast wrote:
>> Nope.  newStdGen is specified in terms of split, which means it
>> leaves the random generator in a state independent of the generator
>> it returns.  Perfectly safe.  (I think you think you used getStdGen).
> I was referring to randoms and randomRs.
> They clobber the generator. You can then get
> a new one using newStdGen, but that forces
> you back into the IO monad.

Oh, of course.  Or call split first.


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