async_t

Give up on dynamic dispatch and get compile-time async traits (with a few bonuses)

async_t provides a #[impl_trait] macro that allows any trait to return existential types; e.g. -> impl Future and a #[async_trait] macro that wraps your async methods under a -> impl Future existential type.

This allows for complete zero-cost async-traits, and allows for recursive existential return types such as Result<impl Display, impl Debug>.

It can also have problems with lifetimes where they have to be specified.

```rust // spawn example

[async_trait]

trait Spawn { // supports self, &self, &mut self and no self async fn spawn() -> JoinHandle<()>; }

[async_trait]

impl Spawn for Spawner { async fn spawn() -> JoinHandle<()> { task::sleep(Duration::from_secs(2)).await; // await inside task::spawn(async { // ... }) } }

async fn spawn() -> JoinHandle<()> { T::spawn().await }

```

```rust

[async_trait]

trait Sleeper { #[unsend] async fn sleep(t: T) -> T; }

[async_trait]

impl Sleeper for () { #[unsend] async fn sleep(t: T) -> T { task::sleep(Duration::from_secs(2)).await; t } } ```

async_t also supports impl return types in traits (async traits are desigared to recursive impl return types)

```rust

[impltrait] // #[asynctrait] can also be used

trait RetDebug { fn ret_debug() -> impl Debug; } ```

Features

async_t supports the boxed feature which will set async_trait to be the one from the async-trait crate from dtolnay.