Sunbeam Studios

Our open-source projects, here for you!

Portugal

https://sunbeam.pt

Repositories

20

Projects Packages

fastrand (2.3.0)

Published 2026-03-26 10:57:53 +00:00 by siennathesane

Installation

Set up this registry in the Cargo configuration file (for example ~/.cargo/config.toml):

[registry]
default = "gitea"

[registries.gitea]
index = "sparse+" # Sparse index
# index = "" # Git

[net]
git-fetch-with-cli = true

To install the package using Cargo, run the following command:

cargo add fastrand@2.3.0

For more information on the Cargo registry, see the documentation.

About this package

A simple and fast random number generator

fastrand

A simple and fast random number generator.

The implementation uses Wyrand, a simple and fast generator but not cryptographically secure.

Examples

Flip a coin:

if fastrand::bool() {
    println!("heads");
} else {
    println!("tails");
}

Generate a random i32:

let num = fastrand::i32(..);

Choose a random element in an array:

let v = vec![1, 2, 3, 4, 5];
let i = fastrand::usize(..v.len());
let elem = v[i];

Sample values from an array with O(n) complexity (n is the length of array):

fastrand::choose_multiple([1, 4, 5], 2);
fastrand::choose_multiple(0..20, 12);

Shuffle an array:

let mut v = vec![1, 2, 3, 4, 5];
fastrand::shuffle(&mut v);

Generate a random Vec or String:

use std::iter::repeat_with;

let v: Vec<i32> = repeat_with(|| fastrand::i32(..)).take(10).collect();
let s: String = repeat_with(fastrand::alphanumeric).take(10).collect();

To get reproducible results on every run, initialize the generator with a seed:

// Pick an arbitrary number as seed.
fastrand::seed(7);

// Now this prints the same number on every run:
println!("{}", fastrand::u32(..));

To be more efficient, create a new Rng instance instead of using the thread-local generator:

use std::iter::repeat_with;

let rng = fastrand::Rng::new();
let mut bytes: Vec<u8> = repeat_with(|| rng.u8(..)).take(10_000).collect();

This crate aims to expose a core set of useful randomness primitives. For more niche algorithms, consider using the fastrand-contrib crate alongside this one.

Features

• std (enabled by default): Enables the std library. This is required for the global generator and global entropy. Without this feature, [Rng] can only be instantiated using the with_seed method.
• js: Assumes that WebAssembly targets are being run in a JavaScript environment.

License

Licensed under either of

• Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)

at your option.

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.

Dependencies

ID	Version
getrandom	^0.2
rand	^0.8
wyhash	^0.5
getrandom	^0.2
getrandom	^0.2
wasm-bindgen-test	^0.3

Keywords

simple fast rand random wyrand

Details

Cargo

2026-03-26 10:57:53 +00:00

0

Stjepan Glavina <stjepang@gmail.com>

Repository Site

Apache-2.0 OR MIT

19 KiB

Assets (1)

fastrand-2.3.0.crate 19 KiB

Versions (1) View all

2.3.0 2026-03-26