On Sun, Aug 20, 2006 at 12:32:05AM +0200, Henning Thielemann wrote:
>
> On Sun, 13 Aug 2006, Marc Weber wrote:
>
> > the rand* function are examples for a typical state usage, arent' they?
> > Is there any reasoon why they are not defined
> > RandomGen g => State g a
> > rather than
> > RandomGen g => (a,a) -> g -> (a,g)
> > ?
>
> It's probably because Control.Monad.State belongs to the MTL which is
> outside Prelude. Nonetheless I find it also more convenient to use the
> State monad for random number generators:
> http://darcs.haskell.org/htam/src/Stochastic.hs
> http://www.haskell.org/pipermail/haskell-cafe/2005-May/009775.html
Exactly, and thanks to the right order of parameters and the result
pair, you can easily use random* functions in a State monad:
do
x <- State random
y <- State (randomR (0, 100))
...
Best regards
Tomasz
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