random-fu- Random number generation



This module provides functions useful for implementing new MonadRandom and RandomSource instances for state-abstractions containing PureMT values (the pure pseudorandom generator provided by the mersenne-random-pure64 package), as well as instances for some common cases.



getRandomWordFromMTRef :: ModifyRef sr m PureMT => sr -> m Word64Source

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

For example, if x :: TVar PureMT, getRandomWordFromMTRef x can be used as a RandomSource in IO, STM, or any monad which is an instance of MonadIO. These functions can also be used to implement additional RandomSource instances for mutable references to PureMT states.

getRandomWordFromMTState :: MonadState PureMT m => m Word64Source

Similarly, getRandomWordFromMTState x can be used in any "state" monad in the mtl sense whose state is a PureMT 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 (e.g., by runState . sample :: Distribution d t => d t -> PureMT -> (t, PureMT). PureMT in the type there can be replaced by StdGen or anything else satisfying MonadRandom (State s) => s).