async callback fn rust

async_cb.rs

use futures::Future;

async fn async_fn_with_async_cb<T: Future>(f: fn(String) -> T) -> T::Output {
    // we do some shit here and then end up with a string
    let x = "`this is the result of something`".to_string();

    f(x).await
}

#[tokio::main]
async fn main() {
    let f = async_fn_with_async_cb(|x: String| async move {
        println!("got {} from func", x);

        // just simulating some async things
        println!("waiting 1 sec...");
        tokio::time::sleep(std::time::Duration::from_secs(1)).await;

        // then we can optionally return something
        "cool beans".to_string()
    });

    let result = f.await;

    println!("{result}");
}