How to use take_while with futures::Stream?

Question

I\'m trying to understand what syntax should I use for take_while() with futures::Stream; crate (0.1.25). Here\'s a piece of code (on playground):

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Answer 1

wait returns an iterator version of the stream, but that iterator remains lazy, which means you need to iterate it to actually execute your closure:

use futures::{stream, Stream}; // 0.1.25

fn into_many(i: i32) -> impl Stream {
    stream::iter_ok(0..i)
}

fn main() {
    println!("start:");
    let foo = into_many(10)
        // .take_while(|x| { x < 10 })
        .map(|x| {
            println!("number={}", x);
            x
        })
        .wait();

    for _ in foo {} // ← this

    println!("finish:");
}

(link to playground)