Random Number Update

Tue Jan 24 17:33:36 UTC 2017

Carter, can you outline how random v2 compares to v1?

Thanks,
Tom

> El 24 ene 2017, a las 10:05, Carter Schonwald <carter.schonwald at gmail.com> escribió:
> 
> This is not a core library or blessed libraries issue. This is a communication issue. You don't want to be involved in the v2 work.  That's fine. 
> 
> 
>> On Tue, Jan 24, 2017 at 10:55 AM <dominic at steinitz.org> wrote:
>> Carter,
>> 
>> I obviously didn’t explain myself very well. We can decouple removing the “bad” RNG from the replacement of it with a “good” RNG. As I thought I said, any new RNG should have the same status as every other RNG and then people can choose; there is no “blessed” RNG. It seems simple (to me at any rate) to decouple these.
>> 
>> More power to your elbow on creating an RNG but I don’t think there should be anything “official” about it. I’ll say it again: I don’t think there should be a random v2 but a random-foobar where foobar is your algorithm.
>> 
>> What do you see sub-optimal about deprecating something that is clearly broken?
>> 
>> I believe I have done my bit for the Haskell Community in trying to resolve what is a tedious situation. I suggest we await the view of the Core Libraries Committee assuming they still see this as part of their scope and take it from there.
>> 
>> Dominic.
>> 
>>> On 24 Jan 2017, at 15:33, Carter Schonwald <carter.schonwald at gmail.com> wrote:
>>> 
>>> Dominic, if you want to remove yourself from maintainer hood that's cool. 
>>> 
>>> I'm keen on finishing up my random v2 release which is a much improved breaking Change.  
>>> 
>>> I spent part of my holiday this year working on it. 
>>> 
>>> Dominic: I'm confused and surprised by your email after we had a one hour phone chat about this topic last week.  
>>> 
>>> I'm disappointed you are still raising concerns I addressed and explained to you last week. 
>>> 
>>> Random v2 is in flight. You are welcome to stop being involved. 
>>> 
>>> On Tue, Jan 24, 2017 at 10:19 AM Adam Bergmark <adam at bergmark.nl> wrote:
>>> On Tue, 24 Jan 2017 at 14:36 Dominic Steinitz <dominic at steinitz.org> wrote:
>>> I wanted to give an update on the status of random numbers in Haskell.
>>> 
>>> 
>>> 
>>> 
>>> 
>>>  1. It is well known that the random number generator package
>>> 
>>> 
>>>     https://hackage.haskell.org/package/random gives unexpected
>>> 
>>> 
>>>     results.
>>> 
>>> 
>>>  2. Most people do *not* use it. I believe
>>> 
>>> 
>>>     https://hackage.haskell.org/package/mwc-random is a popular choice
>>> 
>>> 
>>>     but developers are free to use e.g. Mersenne Twister, PCG
>>> 
>>> 
>>>     (Permuted Congruential Generator), TF (ThreeFish) and many others.
>>> 
>>> 
>>>  3. Approximately 2 years, I made a proposal to replace the algorithm
>>> 
>>> 
>>>     within random (https://hackage.haskell.org/package/random) with
>>> 
>>> 
>>>     that used by tf-random
>>> 
>>> 
>>>     (https://hackage.haskell.org/package/tf-random) which is used by
>>> 
>>> 
>>>     QuickCheck. In summary, the response to this was that someone
>>> 
>>> 
>>>     should do more research with the result that nothing happened.
>>> 
>>> 
>>>  4. In the meantime, random
>>> 
>>> 
>>>     (https://hackage.haskell.org/package/random) is *no longer* a core
>>> 
>>> 
>>>     library. It's just a library with the same status as
>>> 
>>> 
>>>     e.g. mwc-random. However, it has one difference: it uses the name
>>> 
>>> 
>>>     for its module: "System.Random". Other RNGs use
>>> 
>>> 
>>>     "System.Random.MWC", "System.Random.PCG", "System.Random.Mersenne"
>>> 
>>> 
>>>     etc.
>>> 
>>> 
>>> 
>>> 
>>> 
>>> As a maintainer of random
>>> 
>>> 
>>> (https://hackage.haskell.org/package/random), my proposal now is to
>>> 
>>> 
>>> deprecate all of it.
>>> 
>>> 
>>> 
>>> 
>>> 
>>> I am not clear what the policy is on namespace usage. Could every RNG
>>> 
>>> 
>>> use the module name "System.Random"? Or is this somehow reserved? If
>>> 
>>> 
>>> the latter then I propose that *nothing* uses this name and that all
>>> 
>>> 
>>> RNGs should add a suffix indicating which algorithm they use.
>>> 
>>> They *could* use the same namespace but I don't recommend it. If someone depends on two of these packages they would have to use PackageImports. Tools such as doctest break if a package db has module conflicts, even if only one of the packages is listed as a dependency.
>>>  
>>> Cheers,
>>> Adam
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> I note that the Haskell Platform contains tf-random so users of this
>>> 
>>> 
>>> will still be able to generate (better) random numbers.
>>> 
>>> 
>>> 
>>> 
>>> 
>>> If someone comes along in the future, as I hope they do, and
>>> 
>>> 
>>> implements e.g. Guy Steele's splitmix algorithm then this can occupy
>>> 
>>> 
>>> the name "System.Random.Splitmix" and have the package name
>>> 
>>> 
>>> "random-splitmix".
>>> 
>>> 
>>> 
>>> 
>>> 
>>> The advantages of doing this are:
>>> 
>>> 
>>> 
>>> 
>>> 
>>>  1. Neophyte (and experienced) Haskellers do not accidentally use an
>>> 
>>> 
>>>     RNG which gives unexpected results.
>>> 
>>> 
>>>  2. No-one will any longer be able to write blogs or papers about this
>>> 
>>> 
>>>     embarrassing aspect of Haskell.
>>> 
>>> 
>>> 
>>> 
>>> 
>>> I believe the co-maintainer of random
>>> 
>>> 
>>> (https://hackage.haskell.org/package/random), Carter Schonwald, has a
>>> 
>>> 
>>> different view on this matter but it is best he speaks for himself
>>> 
>>> 
>>> rather than me imperfectly trying to reflect his thinking.
>>> 
>>> 
>>> 
>>> 
>>> 
>>> Dominic Steinitz
>>> 
>>> 
>>> dominic at steinitz.org
>>> 
>>> 
>>> http://idontgetoutmuch.wordpress.com
>>> 
>>> 
>>> 
>>> 
>>> 
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>>> 
>>> 
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>>> 
>>> 
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>>> 
>>> 
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>>> 
>>> 
>>> 
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>>> 
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>> 
>> 
>> 
>> Dominic Steinitz
>> dominic at steinitz.org
>> http://idontgetoutmuch.wordpress.com
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