2009/6/9 Krzysztof Skrzętnicki <gte...@gmail.com> > On Tue, Jun 9, 2009 at 16:14, Daniel Fischer<daniel.is.fisc...@web.de> > wrote: > > If you're doing much with random generators, wrap it in a State monad. > > To avoid reinventing the wheel one can use excellent package available > on Hackage: > http://hackage.haskell.org/cgi-bin/hackage-scripts/package/MonadRandom
Please do! Prefer MonadRandom to explicit generator passing: http://lukepalmer.wordpress.com/2009/01/17/use-monadrandom/. Keep computations in MonadRandom, and pull them out with evalRandomIO at the last second. Luke > <http://hackage.haskell.org/cgi-bin/hackage-scripts/package/MonadRandom> > > > The die function simulates the roll of a die, picking a number between 1 > and 6, inclusive, and returning it in the Rand monad. > > Notice that this code will work with any source of random numbers g. > > > > die :: (RandomGen g) => Rand g Int > > die = getRandomR (1,6) > > > > The dice function uses replicate and sequence to simulate the roll of n > dice. > > > > dice :: (RandomGen g) => Int -> Rand g [Int] > > dice n = sequence (replicate n die) > > > > To extract a value from the Rand monad, we can can use evalRandIO. > > > > main = do > > values <- evalRandIO (dice 2) > > putStrLn (show values) > > Best regards > > Krzysztof Skrzętnicki > _______________________________________________ > Haskell-Cafe mailing list > Haskell-Cafe@haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe >
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