Guessing game, error on shadowing guess bind

I'm following the Rust tutorial but I'm stuck on this code (the last snippet in the page):

extern crate rand;

use std::io;
use std::cmp::Ordering;
use rand::Rng;

fn main() {
    println!("Guess the number!");

    let secret_number = rand::thread_rng().gen_range(1, 101);

    println!("The secret number is {}", secret_number);

    loop {
        println!("Please input your guess");

        let mut guess = String::new();

        io::stdin()
            .read_line(&mut guess)
            .expect("Failed to read line");

        let guess: u32 = guess.trim().parse() {
            Ok(num) => num,
            Err(_) => continue,
        }

        println!("You guessed: {}", guess);

        match guess.cmp(&secret_number) {
            Ordering::Less      => println!("Too small!"),
            Ordering::Greater   => println!("Too big!"),
            Ordering::Equal     => {
                println!("You win!");
                break;
            }
        }
    }
}

When I run cargo run I have the following error:

src/main.rs:23:47: 23:48 error: expected one of `.`, `;`, or an operator, found `{`
src/main.rs:23         let guess: u32 = guess.trim().parse() {
                                                             ^

What's the right syntax?