# futures-enum
[](https://crates.io/crates/futures-enum)
[](https://docs.rs/futures-enum)
[](#license)
[](https://www.rust-lang.org)
[](https://github.com/taiki-e/futures-enum/actions?query=workflow%3ACI+branch%3Amaster)
\#\[derive(Future, Stream, Sink, AsyncRead, AsyncWrite, AsyncSeek, AsyncBufRead)\] for enums.
## Usage
Add this to your `Cargo.toml`:
```toml
[dependencies]
futures-enum = "0.1.16"
futures = "0.3"
```
*Compiler support: requires rustc 1.36+*
## Examples
```rust
use futures_enum::*;
use std::future::Future;
#[derive(Future, Stream, Sink, AsyncRead, AsyncWrite, AsyncSeek, AsyncBufRead)]
enum Either<A, B> {
A(A),
B(B),
}
fn foo(x: i32) -> impl Future<Output = i32> {
if x < 0 {
Either::A(async { 1 })
} else {
Either::B(async move { x })
}
}
```
futures-enum works well even if the dependency contains only sub-crates such
as `futures-core`, `futures-io`, `futures-sink`, etc.
See [auto_enums](https://github.com/taiki-e/auto_enums) crate for how to
automate patterns like this.
## Supported traits
- [`Future`](https://doc.rust-lang.org/std/future/trait.Future.html) - [generated code](doc/future.md)
- [`Stream`](https://docs.rs/futures/0.3/futures/stream/trait.Stream.html) - [generated code](doc/stream.md)
- [`Sink`](https://docs.rs/futures/0.3/futures/sink/trait.Sink.html) - [generated code](doc/sink.md)
- [`AsyncRead`](https://docs.rs/futures/0.3/futures/io/trait.AsyncRead.html) - [generated code](doc/async_read.md)
- [`AsyncWrite`](https://docs.rs/futures/0.3/futures/io/trait.AsyncWrite.html) - [generated code](doc/async_write.md)
- [`AsyncSeek`](https://docs.rs/futures/0.3/futures/io/trait.AsyncSeek.html) - [generated code](doc/async_seek.md)
- [`AsyncBufRead`](https://docs.rs/futures/0.3/futures/io/trait.AsyncBufRead.html) - [generated code](doc/async_buf_read.md)
## Related Projects
- [auto_enums]: A library for to allow multiple return types by automatically generated enum.
- [derive_utils]: A procedural macro helper for easily writing [derives macros][proc-macro-derive] for enums.
- [io-enum]: \#\[derive(Read, Write, Seek, BufRead)\] for enums.
- [iter-enum]: \#\[derive(Iterator, DoubleEndedIterator, ExactSizeIterator, Extend)\] for enums.
[auto_enums]: https://github.com/taiki-e/auto_enums
[derive_utils]: https://github.com/taiki-e/derive_utils
[io-enum]: https://github.com/taiki-e/io-enum
[iter-enum]: https://github.com/taiki-e/iter-enum
## License
Licensed under either of [Apache License, Version 2.0](LICENSE-APACHE) or
[MIT license](LICENSE-MIT) at your option.
Unless you explicitly state otherwise, any contribution intentionally submitted
for inclusion in the work by you, as defined in the Apache-2.0 license, shall
be dual licensed as above, without any additional terms or conditions.