012 Rust 异步编程，在 async 块中使用？

示例

• 源码

[dependencies]
futures = "0.3"      

• 配置文件

use futures;

async fn foo() -> Result<(), String>{
    "foo";
    Ok(())
}

async fn func() -> Result<(), String>{

    let fut = async {
        foo().await?;
        Ok::<(), String>(()) // <- note the explicit type annotation here
        //Ok(()) // <- note the explicit type annotation here
    };

    fut.await
}

fn main() {
    let _ = futures::executor::block_on(func());
    println!("Hello, world!");

}