A Rust library for random number generation.
Rand provides utilities to generate random numbers, to convert them to useful types and distributions, and some randomness-related algorithms.
The core random number generation traits of Rand live in the rand_core crate but are also exposed here; RNG implementations should prefer to use
rand_core while most other users should depend on
Add this to your
[dependencies] rand = "0.6"
To get started using Rand, see The Book.
The Rand lib is not yet stable, however we are careful to limit breaking changes and warn via deprecation wherever possible. Patch versions never introduce breaking changes. The following minor versions are supported:
seqmodule, moving most PRNGs to external crates, and many small changes.
rand_core, and deprecating
Randand the previous distribution traits).
A detailed changelog is available.
When upgrading to the next minor series (especially 0.4 → 0.5), we recommend reading the Upgrade Guide.
Since version 0.5, Rand requires Rustc version 1.22 or greater. Rand 0.4 and 0.3 (since approx. June 2017) require Rustc version 1.15 or greater. Subsets of the Rand code may work with older Rust versions, but this is not supported.
Travis CI always has a build with a pinned version of Rustc matching the oldest supported Rust release. The current policy is that this can be updated in any Rand release if required, but the change must be noted in the changelog.
To avoid bumping the required version unnecessarily, we use a
build.rs script to auto-detect the compiler version and enable certain features or change code paths automatically. Since this makes it easy to unintentionally make use of features requiring a more recent Rust version, we recommend testing with a pinned version of Rustc if you require compatibility with a specific version.
Rand is built with only the
std feature enabled by default. The following optional features are available:
alloccan be used instead of
logenables some logging via the
nightlyenables all unstable features (
serde1enables serialization for some types, via Serde version 1.
simd_supportenables uniform sampling of SIMD types (integers and floats).
stdwebenables support for
wasm-bindgenenables support for
no_std mode is activated by setting
default-features = false; this removes functionality depending on
random()are not available, as they require thread-local storage and an entropy source.
JitterRngcode is still present, but a nanosecond timer must be provided via
FromEntropytrait (user must provide a seed).
logfunctions are not provided in
seq-uence module are unavailable, unless the
allocfeature is used (several APIs and many implementations require
Rand is distributed under the terms of both the MIT license and the Apache License (Version 2.0).