> Async traits come to mind immediately,
I agree that being able to use `async` inside of traits would be very useful, and hopefully we will get it soon.
> generally needing more capability to existentially quantify Future types without penalty
Could you clarify what you mean by that? Both `impl Future` and `dyn Future` exist, do they not work for your use case?
> Async function types are a mess to write out.
Are you talking about this?
fn foo() -> impl Future<Output = u32>
Or this?
async fn foo() -> u32
> More control over heap allocations in async/await futures (we currently have to Box/Pin more often than necessary).
I'm curious about your code that needs to extensively Box. In my experience Boxing is normally just done 1 time when spawning the Future.
> Async drop.
That would be useful, but I wouldn't call the lack of it "half-baked", since no other mainstream language has it either. It's just a nice-to-have.
> Better cancellation.
What do you mean by that? All Futures/Streams/etc. support cancellation out of the box, it's just automatic with all Futures/Streams.
If you want really explicit control you can use something like `abortable`, which gives you an AbortHandle, and then you can call `handle.abort()`
Rust has some of the best cancellation support out of any async language I've used.
> Async iteration.
Nicer syntax for Streams would be cool, but the combinators do a good job already, and StreamExt already has a similar API as Iterator.
I agree that being able to use `async` inside of traits would be very useful, and hopefully we will get it soon.
> generally needing more capability to existentially quantify Future types without penalty
Could you clarify what you mean by that? Both `impl Future` and `dyn Future` exist, do they not work for your use case?
> Async function types are a mess to write out.
Are you talking about this?
Or this? > More control over heap allocations in async/await futures (we currently have to Box/Pin more often than necessary).I'm curious about your code that needs to extensively Box. In my experience Boxing is normally just done 1 time when spawning the Future.
> Async drop.
That would be useful, but I wouldn't call the lack of it "half-baked", since no other mainstream language has it either. It's just a nice-to-have.
> Better cancellation.
What do you mean by that? All Futures/Streams/etc. support cancellation out of the box, it's just automatic with all Futures/Streams.
If you want really explicit control you can use something like `abortable`, which gives you an AbortHandle, and then you can call `handle.abort()`
Rust has some of the best cancellation support out of any async language I've used.
> Async iteration.
Nicer syntax for Streams would be cool, but the combinators do a good job already, and StreamExt already has a similar API as Iterator.