Rust

fn main() {
    let mut button = Button::new();
    let mut led = Led::new();
    loop {
        if button.is_pressed() {
            led.on();
        } else {
            led.off();
        }
    }
}

static BUTTON: Mutex<Option<Button>> = Mutex::new(None);
static LED: Mutex<Option<Led>> = Mutex::new(None);
fn main() {
    LED.lock().replace(Led::new());
    BUTTON.lock().replace(Button::new());
    setup_irq(button_event); // Magic
}

fn button_event() {
    if BUTTON.lock().as_mut().unwrap().is_pressed() {
        LED.lock().as_mut().unwrap().on();
    } else {
        LED.lock().as_mut().unwrap().off();
    }
}

async fn main() {
    let mut button = Button::new();
    let mut led = Led::new();
    loop {
        button.wait_changed().await;
        if button.is_pressed() {
            led.on();
        } else {
            led.off();
        }
    }
}