# Using the Nois Toolbox in a CosmWasm smart-contract

#### coinflip

Takes a randomness and returns the result of a coinflip (heads or tails)

``````#![allow(unused)]
fn main() {
use nois::coinflip;

let side = coinflip(randomness);
}
if side.is_tails(){
println!("tails")
}
}``````

#### int_in_range

Derives a random integer in the given range. Use this method to avoid a modulo bias.

``````#![allow(unused)]
fn main() {
use nois::int_in_range;

// Half-open interval [1, 7)
let dice1 = int_in_range(randomness, 1..7);
assert!(dice1 >= 1);
assert!(dice1 < 7);

// Closed interval [1, 6]
let dice2 = int_in_range(randomness, 1..=6);
assert!(dice2 >= 1);
assert!(dice2 <= 6);
}``````

#### ints_in_range

Derives random integers in the given range. Use this method to avoid a modulo bias. Using this is potentially more efficient than multiple calls of int_in_range.

``````#![allow(unused)]
fn main() {
use nois::ints_in_range;

let [dice1, dice2] = ints_in_range(randomness, 1..=6);
assert!(dice1 >= 1 && dice1 <= 6);
assert!(dice2 >= 1 && dice2 <= 6);
}``````

#### random_decimal

Returns a Decimal d with 0 <= d < 1

``````#![allow(unused)]
fn main() {
use nois::random_decimal;

let d = random_decimal(randomness);
}``````

#### shuffle

Shuffles a vector using the Fisher-Yates algorithm

``````#![allow(unused)]
fn main() {
use nois::shuffle;

//We are randomly shuffling a vector of integers [1,2,3,4]
let mut data = vec![1, 2, 3, 4];
shuffle(randomness, &mut data);
// The length of the vector is the same but the order of the elements has changed
assert_eq!(data.len(), 4);
assert_ne!(data, vec![1, 2, 3, 4]);
}``````

#### sub_randomness_with_key

Takes a randomness and a key. Returns an arbitrary number of sub-randomnesses. The key is mixed into the randomness such that calling this function with different keys leads to different outputs. Calling it with the same key and randomness leads to the same outputs.

``````#![allow(unused)]
fn main() {
use nois::{sub_randomness_with_key, int_in_range};

let mut provider = sub_randomness_with_key(randomness, "Key");

let dice1_subrandomness = provider.provide();
let dice2_subrandomness = provider.provide();

let dice1_result = int_in_range(dice1_subrandomness, 1..7);
let dice2_result = int_in_range(dice2_subrandomness, 1..7);
}``````

#### sub_randomness

Takes a randomness and a key. Returns an arbitrary number of sub-randomnesses. This is equivalent to calling sub_randomness_with_key with key b"^default^".

``````#![allow(unused)]
fn main() {
use nois::{sub_randomness, int_in_range};

let mut provider = sub_randomness(randomness);

let dice1_subrandomness = provider.provide();
let dice2_subrandomness = provider.provide();

let dice1_result = int_in_range(dice1_subrandomness, 1..7);
let dice2_result = int_in_range(dice2_subrandomness, 1..7);
}``````