How to use async iterators in Rust

Use async iterators in Rust by implementing the Stream trait from the futures crate or using the async-stream crate to yield items asynchronously.

use async_stream::stream;

async fn async_numbers() {
    let mut count = 0;
    let s = stream! {
        for i in 0..5 {
            count += 1;
            yield i;
        }
    };
    // Consume the stream
    while let Some(n) = s.next().await {
        println!("Got: {}", n);
    }
}

Install the crate first: cargo add async-stream.

Async iterators let you process a list of items one by one without blocking your program while waiting for data. Think of it like a conveyor belt that delivers packages as they arrive, rather than waiting for the whole truck to unload before starting. You use this when fetching data from a network or reading large files where you want to handle each piece immediately.