Rust Async Closure Test

main.rs

#![feature(async_closure)]
use futures_util::future::join_all;
use std::{iter::zip, time::Duration};
use tokio::time::sleep;

#[tokio::main]
async fn main() {
    let ids = [1, 2, 3, 4];
    let durations = [200, 100, 300, 250];

    join_all(
        zip(ids, durations)
            .map(async move |(id, duration)| {
                let async_fn = hello(id, Duration::from_millis(duration)).await;
                async_fn
            })
            .collect::<Vec<_>>(),
    )
    .await;
}

async fn hello(id: usize, duration: Duration) {
    sleep(duration).await;
    println!("Hello, {id}");
}

Result

   Compiling playground v0.0.1 (/playground)
    Finished dev [unoptimized + debuginfo] target(s) in 1.42s
     Running `target/debug/playground`

Hello, 2
Hello, 1
Hello, 4
Hello, 3