#futures #async #macro #macros


Definition of the #[async] macro for the futures-rs crate as well as a few other assorted macros

1 unstable release

Uses old Rust 2015

0.2.1 Apr 19, 2018


542 lines


Zero-cost asynchronous programming in Rust

Build Status Crates.io Rustc Version

Documentation | Website

futures-rs is a library providing the foundations for asynchronous programming in Rust. It includes key trait definitions like Stream, as well as utilities like join!, select!, and various futures combinator methods which enable expressive asynchronous control flow.


Add this to your Cargo.toml:

futures = "0.3"

Now, you can use futures-rs:

use futures::future::Future;

The current futures-rs requires Rust 1.41 or later.

Feature std

Futures-rs works without the standard library, such as in bare metal environments. However, it has a significantly reduced API surface. To use futures-rs in a #[no_std] environment, use:

futures = { version = "0.3", default-features = false }


This project is licensed under either of

at your option.


Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in futures-rs by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.


~43K SLoC