Awesome
Rand
Rand is a set of crates supporting (pseudo-)random generators:
- Built over a standard RNG trait:
rand_core::RngCore
- With fast implementations of both strong and
small generators:
rand::rngs
, and more RNGs:rand_chacha
,rand_xoshiro
,rand_pcg
, rngs repo rand::rng
is an asymptotically-fast, automatically-seeded and reasonably strong generator available on allstd
targets- Direct support for seeding generators from the
getrandom
crate
With broad support for random value generation and random processes:
Standard
random value sampling,Uniform
-ranged value sampling and more- Samplers for a large number of non-uniform random number distributions via our own
rand_distr
and via thestatrs
- Random processes (mostly choose and shuffle) via
rand::seq
traits
All with:
- Portably reproducible output
#[no_std]
compatibility (partial)- Many performance optimisations thanks to contributions from the wide user-base
Rand is not:
- Small (LOC). Most low-level crates are small, but the higher-level
rand
andrand_distr
each contain a lot of functionality. - Simple (implementation). We have a strong focus on correctness, speed and flexibility, but not simplicity. If you prefer a small-and-simple library, there are alternatives including fastrand and oorandom.
- A cryptography library. Rand provides functionality for generating unpredictable random data (potentially applicable depending on requirements) but does not provide high-level cryptography functionality.
Rand is a community project and cannot provide legally-binding guarantees of security.
Documentation:
Usage
Add this to your Cargo.toml
:
[dependencies]
rand = "0.8.5"
To get started using Rand, see The Book.
Versions
Rand is mature (suitable for general usage, with infrequent breaking releases which minimise breakage) but not yet at 1.0. Current versions are:
- Version 0.8 was released in December 2020 with many small changes.
- Version 0.9 is in development with many small changes.
See the CHANGELOG or Upgrade Guide for more details.
Crate Features
Rand is built with these features enabled by default:
std
enables functionality dependent on thestd
liballoc
(implied bystd
) enables functionality requiring an allocatorgetrandom
(implied bystd
) is an optional dependency providing the code behindrngs::OsRng
std_rng
enables inclusion ofStdRng
,ThreadRng
Optionally, the following dependencies can be enabled:
log
enables logging via log
Additionally, these features configure Rand:
small_rng
enables inclusion of theSmallRng
PRNGnightly
includes some additions requiring nightly Rustsimd_support
(experimental) enables sampling of SIMD values (uniformly random SIMD integers and floats), requiring nightly Rust
Note that nightly features are not stable and therefore not all library and
compiler versions will be compatible. This is especially true of Rand's
experimental simd_support
feature.
Rand supports limited functionality in no_std
mode (enabled via
default-features = false
). In this case, OsRng
and from_os_rng
are
unavailable (unless getrandom
is enabled), large parts of seq
are
unavailable (unless alloc
is enabled), and ThreadRng
is unavailable.
Portability and platform support
Many (but not all) algorithms are intended to have reproducible output. Read more in the book: Portability.
The Rand library supports a variety of CPU architectures. Platform integration is outsourced to getrandom.
WASM support
Seeding entropy from OS on WASM target wasm32-unknown-unknown
is not
automatically supported by rand
or getrandom
. If you are fine with
seeding the generator manually, you can disable the getrandom
feature
and use the methods on the SeedableRng
trait. To enable seeding from OS,
either use a different target such as wasm32-wasi
or add a direct
dependency on getrandom
with the js
feature (if the target supports
JavaScript). See
getrandom#WebAssembly support.
License
Rand is distributed under the terms of both the MIT license and the Apache License (Version 2.0).
See LICENSE-APACHE and LICENSE-MIT, and COPYRIGHT for details.