How to convert sync code to async

To convert sync code to async in Rust, add the async keyword to the function signature and use .await on any asynchronous operations.

use trpl::Html;

async fn page_title(url: &str) -> Option<String> {
    let response_text = trpl::get(url).await.text().await;
    Html::parse(&response_text)
        .select_first("title")
        .map(|title| title.inner_html())
}

In main, you must run the async function using a runtime like tokio:

#[tokio::main]
async fn main() {
    let title = page_title("https://example.com").await;
    println!("{title:?}");
}

Converting sync code to async tells your program to pause and wait for slow tasks, like network requests, without freezing the whole application. Think of it like ordering food at a restaurant: instead of standing at the kitchen door waiting for your meal, you sit at your table and the server brings it to you when it's ready. This allows your program to handle other tasks while waiting for data.