Data.Random.Source.StdGen

This module provides functions useful for implementing new MonadRandom and RandomSource instances for state-abstractions containing StdGen values (the pure pseudorandom generator provided by the System.Random module in the "random" package), as well as instances for some common cases.

Documentation

data StdGen

Instances

Read StdGen

Show StdGen

RandomGen StdGen

(Monad m, ModifyRef (IORef StdGen) m StdGen) => RandomSource m (IORef StdGen)

(Monad m, ModifyRef (STRef s StdGen) m StdGen) => RandomSource m (STRef s StdGen)

(Monad m1, ModifyRef (Ref m2 StdGen) m1 StdGen) => RandomSource m1 (Ref m2 StdGen)

Monad m => MonadRandom (StateT StdGen m)

Monad m => MonadRandom (StateT StdGen m)

mkStdGen :: Int -> StdGen

newStdGen :: IO StdGen

getRandomPrimFromStdGenIO :: Prim a -> IO a

getRandomPrimFromRandomGenRef :: (Monad m, ModifyRef sr m g, RandomGen g) => sr -> Prim a -> m a

Given a mutable reference to a RandomGen generator, we can make a RandomSource usable in any monad in which the reference can be modified.

See Data.Random.Source.PureMT.getRandomPrimFromMTRef for more detailed usage hints - this function serves exactly the same purpose except for a StdGen generator instead of a PureMT generator.

getRandomPrimFromRandomGenState :: forall g m a. (RandomGen g, MonadState g m) => Prim a -> m a

Similarly, getRandomWordFromRandomGenState x can be used in any "state" monad in the mtl sense whose state is a RandomGen generator. Additionally, the standard mtl state monads have MonadRandom instances which do precisely that, allowing an easy conversion of RVars and other Distribution instances to "pure" random variables.

Again, see Data.Random.Source.PureMT.getRandomPrimFromMTState for more detailed usage hints - this function serves exactly the same purpose except for a StdGen generator instead of a PureMT generator.