Simple flat_map example - filtering data from list of structs

main.rs

#[derive(Debug)]
struct Task {
    b: u8,
    c: String,
}

#[derive(Debug)]
struct Day {
    a: u8,
    tasks: Vec<Task>,
}

fn main() {
    println!("Hello, world!");
    let t1 = Task { b: 1, c: "ahoj".to_string() };
    let t2 = Task { b: 2, c: "ahojjjj".to_string() };
    let t3 = Task { b: 2, c: "bbbbjjj".to_string() };
    let t4 = Task { b: 2, c: "ccccjjj".to_string() };
    let day1 = Day { a: 3, tasks: vec![t1, t3, t4]};
    let day2 = Day { a: 4, tasks: vec![t2]};
    let days = vec![day1, day2];
    let tasks: Vec<&Task> = days.iter()
                                .flat_map(|x| &x.tasks)
                                .filter(|x| x.b == 2)
                                .collect();
    println!("{:?}", tasks);
}