[Haskell] System.Random

Wolfgang Jeltsch wolfgang at jeltsch.net
Tue Mar 2 14:16:23 EST 2004

Am Dienstag, 2. März 2004 13:47 schrieb Jerzy Karczmarczuk:
> Simon Marlow wrote:
> >>why is the Random module situated under System?  Wouldn't
> >>something like Data be more adequate?
> >
> > There is usually an external source of randomness, which is why the
> > library in placed in System rather than Data.  A purely functional
> > random library would be rather less useful...
> Now, I don't understand this at all...
> All the development of the Random stuff in all languages has nothing
> of random whatsoever. Perhaps *some* people like to seed the generator
> with the clock time, but most *real* developers *known to me* usually
> choose the seed deterministically, in order to reproduce the sequence,
> until the program is ready to run in the end-user environment.
> Anyway, conceptually, the behaviour of random generators is very far from
> any "external source of randomness", so the question 'why "System"' for
> me remains valid. The module Random might of course use Time or similar
> entities for the randomization/initialization, but this is a contingency.
> Jerzy Karczmarczuk

Yes.  My question was based on the fact that most of the stuff in Random has 
really nothing to do with the system.  The main random stuff is purely 
functional.  Things like getStdGen are rather nice additions to the core 


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