random package:tf-random

random :: (Random a, RandomGen g) => g -> (a, g)
tf-random System.Random.TF.Instances
class Random a
tf-random System.Random.TF.Instances
randomEnum :: (Enum a, RandomGen g) => (a, a) -> g -> (a, g)
tf-random System.Random.TF.Instances
randomR :: (Random a, RandomGen g) => (a, a) -> g -> (a, g)
tf-random System.Random.TF.Instances
randomRs :: (Random a, RandomGen g) => (a, a) -> g -> [a]
tf-random System.Random.TF.Instances
randoms :: (Random a, RandomGen g) => g -> [a]
tf-random System.Random.TF.Instances
class RandomGen g
tf-random System.Random.TF.Gen
Alternative RandomGen class with a modified next operation, and added splitn and level operations. Using the generator requires that no more than one operation is called on the same generator state, as the implementation does not guarantee pseudorandomness otherwise. As an exception, calling splitn many times on the same generator state is allowed as long as the 'bits' argument is the same for all the calls.
package tf-random
Uses
High-quality splittable pseudorandom number generator This package contains an implementation of a high-quality splittable pseudorandom number generator. The generator is based on a cryptographic hash function built on top of the ThreeFish block cipher. See the paper Splittable Pseudorandom Number Generators Using Cryptographic Hashing by Claessen, Pałka for details and the rationale of the design. The package provides the following:
  • A splittable PRNG that implements the standard System.Random.RandomGen class.
  • The generator also implements an alternative version of the System.Random.TF.Gen.RandomGen class (exported from System.Random.TF.Gen), which requires the generator to return pseudorandom integers from the full 32-bit range, and contains an n-way split function.
  • An alternative version of the Random class is provided, which is linked to the new RandomGen class, together with Random instances for some integral types.
  • Two functions for initialising the generator with a non-deterministic seed: one using the system time, and one using the /dev/urandom UNIX special file.
The package uses an adapted version of the reference C implementation of ThreeFish from the reference package of the Skein hash function (https://www.schneier.com/skein.html), originally written by Doug Whiting. Please note that even though the generator provides very high-quality pseudorandom numbers, it has not been designed with cryptographic applications in mind.