extern crate futures; // 0.1.25
extern crate tokio; // 0.1.14

use futures::future::lazy;
use futures::future::*;
use std::result::Result::Ok;
use tokio::prelude::Future;

struct MyStruct {
    a: String,
}

impl MyStruct {
    fn new() -> Self {
        Self {
            a: "Hello".to_string(),
        }
    }
    // recursive function
    fn rec(&self, b: u32) -> Box<dyn Future<Item = (), Error = ()> + Send> {
        println!("{}", b);
        Box::new(ok("Example").and_then(move |_| {
            lazy(move || {
                if b > 1 {
                    tokio::spawn(self.rec(b - 1));
                }
                Ok(())
            })
        }))
    }
}

fn main() {
    let my_struct = MyStruct::new();
    tokio::run(my_struct(10));
}