rust_book_code 0.2.1

The code of rust book
Documentation 
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pub fn match_one_pattern() {
    let config_max = Some(3u8);
    match config_max {
        Some(max) => println!("The maximum is configured to be {}", max),
        _ => (),
    }
}

pub fn if_let() {
    let config_max = Some(3u8);
    if let Some(max) = config_max {
        println!("The maximum is configured to be {}", max);
    }
}

#[derive(Debug)]
enum UsState {
    Alabama,
    Alaska,
    // --snip--
}

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

pub fn coin() {
    let coin = Coin::Penny;
    let mut count = 0;
    match coin {
        Coin::Quarter(state) => println!("State quarter from {:?}!", state),
        _ => count += 1,
    }
    println!("{}", count);

    let coin = Coin::Quarter(UsState::Alabama);
    let mut count = 0;
    if let Coin::Quarter(state) = coin {
        println!("State quarter from {:?}!", state);
    } else {
        count += 1;
    }
    println!("{}", count);
}