random-source-0.3.0.6: Generic basis for random number generators

Data.Random.Internal.Source

Synopsis

Documentation

data Prim a whereSource

A Prompt GADT describing a request for a primitive random variate. Random variable definitions will request their entropy via these prompts, and entropy sources will satisfy those requests. The functions in Data.Random.Source.Internal.TH extend incomplete entropy-source definitions to complete ones, essentially defining a very flexible implementation-defaulting system.

Some possible future additions: PrimFloat :: Prim Float PrimInt :: Prim Int PrimPair :: Prim a -> Prim b -> Prim (a :*: b) PrimNormal :: Prim Double PrimChoice :: [(Double :*: a)] -> Prim a PrimBytes :: !Int -> Prim ByteString

Unfortunately, I cannot get Haddock to accept my comments about the data constructors, but hopefully they should be reasonably self-explanatory.

Constructors

 PrimWord8 :: Prim Word8 PrimWord16 :: Prim Word16 PrimWord32 :: Prim Word32 PrimWord64 :: Prim Word64 PrimDouble :: Prim Double PrimNByteInteger :: !Int -> Prim Integer

Instances

 Typeable1 Prim Show (Prim a)

class Monad m => MonadRandom m whereSource

A typeclass for monads with a chosen source of entropy. For example, RVar is such a monad - the source from which it is (eventually) sampled is the only source from which a random variable is permitted to draw, so when directly requesting entropy for a random variable these functions are used.

Minimum implementation is either the internal getRandomPrim or all other functions. Additionally, this class's interface is subject to extension at any time, so it is very, very strongly recommended that the monadRandom Template Haskell function be used to implement this function rather than directly implementing it. That function takes care of choosing default implementations for any missing functions; as long as at least one function is implemented, it will derive sensible implementations of all others.

To use monadRandom, just wrap your instance declaration as follows (and enable the TemplateHaskell and GADTs language extensions):

instance MonadRandom FooM where
getRandomDouble = return pi
getRandomWord16 = return 4
{- etc... -}
|])

Methods

getRandomPrim :: Prim t -> m tSource

Generate a random value corresponding to the specified primitive.

This is an internal interface; use at your own risk. It may change or disappear at any time.

Generate a uniformly distributed random Word8

Generate a uniformly distributed random Word16

Generate a uniformly distributed random Word32

Generate a uniformly distributed random Word64

Generate a uniformly distributed random Double in the range 0 <= U < 1

Generate a uniformly distributed random Integer in the range 0 <= U < 256^n

Instances

 MonadRandom IO Monad m0 => MonadRandom (StateT PureMT m0) Monad m => MonadRandom (StateT StdGen m) Monad m0 => MonadRandom (StateT PureMT m0) Monad m => MonadRandom (StateT StdGen m)

class Monad m => RandomSource m s whereSource

A source of entropy which can be used in the given monad.

Minimum implementation is either the internal getRandomPrimFrom or all other functions. Additionally, this class's interface is subject to extension at any time, so it is very, very strongly recommended that the randomSource Template Haskell function be used to implement this function rather than directly implementing it. That function takes care of choosing default implementations for any missing functions; as long as at least one function is implemented, it will derive sensible implementations of all others.

To use randomSource, just wrap your instance declaration as follows (and enable the TemplateHaskell, MultiParamTypeClasses and GADTs language extensions, as well as any others required by your instances, such as FlexibleInstances):

\$(randomSource [d|
instance RandomSource FooM Bar where
{- at least one RandomSource function... -}
|])

Methods

getRandomPrimFrom :: s -> Prim t -> m tSource

Generate a random value corresponding to the specified primitive.

This is an internal interface; use at your own risk. It may change or disappear at any time.

getRandomWord8From :: s -> m Word8Source

Generate a uniformly distributed random Word8

getRandomWord16From :: s -> m Word16Source

Generate a uniformly distributed random Word16

getRandomWord32From :: s -> m Word32Source

Generate a uniformly distributed random Word32

getRandomWord64From :: s -> m Word64Source

Generate a uniformly distributed random Word64

getRandomDoubleFrom :: s -> m DoubleSource

Generate a uniformly distributed random Double in the range 0 <= U < 1

getRandomNByteIntegerFrom :: s -> Int -> m IntegerSource

Generate a uniformly distributed random Integer in the range 0 <= U < 256^n

Instances