What do I need?

Rust 1.85 or newer. vrd's manifest declares 1.70, but the rand 0.10 crate it depends on needs 1.85: on Rust 1.80 the build stops while reading rand_core's manifest, and on 1.85 it succeeds.

How do I add it?

cargo add vrd

or in Cargo.toml:

[dependencies]
vrd = "0.0.12"

0.0.12 is the latest release on crates.io. The default feature is std, which turns on alloc.

How do I draw numbers?

use vrd::Random;

fn main() {
    let mut rng = Random::new();           // Xoshiro256++, seeded by the OS

    println!("u32:        {}", rng.rand());
    println!("u64:        {}", rng.u64());
    println!("[1, 100]:   {}", rng.int(1, 100));
    println!("[0.0, 1.0): {}", rng.float());
    println!("choice:     {:?}", rng.choose(&[10, 20, 30]));
}

Random::new() asks the operating system for a seed and may panic if none is available; Random::from_seed never does.

How do I get the same numbers every run?

Seed the generator yourself:

use vrd::Random;

let mut rng = Random::from_u64_seed(0xCAFE_BABE);
let first = rng.rand(); // 2783027749 with vrd 0.0.12

Random::from_seed([u8; 32]) takes a 32-byte seed instead. Neither allocates.

How do I use another backend?

Call its constructor; the methods stay the same.

use vrd::Random;

let mut mt = Random::new_mersenne_twister(); // MT19937
let mut pcg = Random::new_pcg32();           // needs the pcg feature
let mut secure = Random::new_secure();       // ChaCha20, needs the crypto feature
let token = secure.base64_token(32);

[dependencies]
vrd = { version = "0.0.12", features = ["pcg", "crypto"] }

How do I build for an embedded target?

Turn off the default features and seed manually:

[dependencies]
vrd = { version = "0.0.12", default-features = false }

use vrd::Random;

let mut rng = Random::from_seed([0x42u8; 32]);
let n = rng.rand();

Where next?

The API guide for every method and Cargo feature.
The migration guide if you are coming from rand, fastrand or an older vrd.
The full API reference on docs.rs.

Your first random numbers