extern crate futures;

use futures::future::*;
use futures::{Stream, stream,  Async};

fn main() {
    // generate FutureResult
    let future_of_ok = ok::<u32, u32>(1); // immediate value of a successful computation
    let future_of_err = err::<u32, u32>(1); // immediate value of a failed computation
    // convert std::result::Result to FutureResult
    let future_of_result = result::<u32, u32>(Ok(1));

    // convert Iterator into a stream
    let mut stream = stream::iter_ok::<_, ()>(vec![17, 19]);
    // poll(pull out)
    assert_eq!(Ok(Async::Ready(Some(17))), stream.poll());

    let mut stream = stream::iter_result(vec![Ok(17), Err(false), Ok(19)]);
    assert_eq!(Ok(Async::Ready(Some(17))), stream.poll());
    assert_eq!(Err(false), stream.poll());
    assert_eq!(Ok(Async::Ready(Some(19))), stream.poll());
    assert_eq!(Ok(Async::Ready(None)), stream.poll());


    let mut stream = stream::once::<(), _>(Err(17));
    assert_eq!(Err(17), stream.poll());
    assert_eq!(Ok(Async::Ready(None)), stream.poll());

    let mut a = lazy(|| ok::<u32, u32>(1));
    println!("{:?}", a.poll()); // Ok(Async::Ready(1))
    let mut b = lazy(|| -> FutureResult<u32, u32> {panic!("oh no")});
    drop(b);
    //println!("{:?}", b.poll())
}