rust-book/enums/src/main.rs

#[derive(Debug)]
enum UsState {
    Alabama,
    Alaska,
    Arizona,
    Arkansaw,
    California,
    Colorado,
    Connecticut,
    Delaware,
    Florida,
    Georgia,
    Hawaii,
    Idaho,
    Illinois,
    Indianan,
    Iowa,
    Kansas,
    Kentucky,
    Louisiana,
    Maine,
    Maryland,
    Massachusetts,
    Michigan,
    Minnesota,
    Mississippi,
    Missouri,
    Montana,
    Nebraska,
    Nevada,
    New_Hampshire,
    New_Jersey,
    New_Mexico,
    New_York,
    North_Carolina,
    North_Dakota,
    Ohio,
    Oklahoma,
    Oregon,
    Pennsylvania,
    Rhode_Island,
    South_Carolina,
    South_Dakota,
    Tennessee,
    Texas,
    Utah,
    Vermont,
    Virginia,
    Washington,
    West_Virginia,
    Wisconsin,
    Wyoming,
}

enum Coin {
    Penny,
    Nickel,
    Dime,
    Quarter(UsState),
}

fn value_in_cents(coin: Coin) -> u32 {
    match coin {
        Coin::Penny => {
            println!("Lucky penny!");
            1
        },
        Coin::Nickel => 5,
        Coin::Dime => 10,
        Coin::Quarter(state) => {
            println!("State quarter from {:?}!", state);
            25
        },
    }
}

fn count_non_quarters(count: &mut u32, coin: Coin) {
    // If let is like matching on one condition of a match statement
    if let Coin::Quarter(state) = coin {
        println!("State quarter from {:?}!", state);
    } else {
        count += 1;
    }
}

fn plus_one(x: Option<i32>) -> Option<i32> {
    match x {
        None => None, // Match is exhaustive, must define the 'None' case
        Some(i) => Some(i + 1),
    }
}

fn main() {
    println!("Hello, world!");
}