Crate spinoso_random

An implementation of Ruby’s pseudo-random number generator, or PRNG.

The PRNG produces a deterministic sequence of bits which approximate true randomness. The sequence may be represented by integers, floats, or binary strings.

The generator may be initialized with either a system-generated or user-supplied seed value.

PRNGs are currently implemented as a modified Mersenne Twister with a period of 2**19937-1.

Implementation notes

This RNG reproduces the same random bytes and floats as MRI. It may differ when returning elements confined to a distribution.

Examples

Generate integers:

use spinoso_random::Random;

let seed = [627457_u32, 697550, 16438, 41926];
let mut random = Random::with_array_seed(seed);
let rand = random.next_int32();

Generate random numbers in a range:

use spinoso_random::{rand, Max, Rand, Random};

let mut random = Random::new()?;
let max = Max::Integer(10);
let mut rand = rand(&mut random, max)?;
assert!(matches!(rand, Rand::Integer(x) if x < 10));

no_std

This crate is no_std compatible when built without the std feature. This crate does not depend on alloc.

Crate features

All features are enabled by default.

• rand-method - Enables range sampling methods for the rand() function. Activating this feature also activates the rand_core feature. Dropping this feature removes the rand dependency.
• rand_core - Enables implementations of RngCore on the Random type. Dropping this feature removes the rand_core dependency.
• std - Enables a dependency on the Rust Standard Library. Activating this feature enables std::error::Error impls on error types in this crate.

Structs

• ArgumentError
  Error that indicates a random number could not be generated with the given bounds.
• InitializeError
  Error that indicates a Random random number generator failed to initialize.
• NewSeedError
  Error that indicates the system source of cryptographically secure randomness failed to read sufficient bytes to create a new seed.
• Random
  Random provides an interface to Ruby’s pseudo-random number generator, or PRNG.
• UrandomError
  Error that indicates the system source of cryptographically secure randomness failed to read the requested bytes.

Enums

• Error
  Sum type of all errors possibly returned from Random functions.
• Max
  A range constraint for generating random numbers.
• Rand
  A generated random number.

Functions

• new_seed
  Read a new Random seed, using platform-provided randomness.
• rand
  Generate random numbers bounded from below by 0 and above by the given max.
• seed_to_key
  Convert a byte array into a reseeding key of u32s.
• urandom
  Read random bytes, using platform-provided randomness.