Merge pull request #1024 from joshtriplett/remove-pre-std-future-docs

futures now re-exports std Future; remove docs about differences

docs/src/SUMMARY.md

@@ -2,7 +2,6 @@
 
 - [Introduction](./introduction.md)
   - [Welcome to `async-std`!](./overview/async-std.md)
-  - [`std::future` and `futures-rs`](./overview/std-and-library-futures.md)
   - [Stability guarantees](./overview/stability-guarantees.md)
 - [Async concepts using async-std](./concepts.md)
   - [Futures](./concepts/futures.md)

docs/src/overview/std-and-library-futures.md

@@ -1,27 +0,0 @@
-# `std::future` and `futures-rs`
-
-Rust has two kinds of types commonly referred to as `Future`: 
-
-
-- the first is `std::future::Future` from Rust’s [standard library](https://doc.rust-lang.org/std/future/trait.Future.html). 
-- the second is `futures::future::Future` from the [futures-rs crate](https://docs.rs/futures/0.3/futures/prelude/trait.Future.html). 
-
-The future defined in the [futures-rs](https://docs.rs/futures/0.3/futures/prelude/trait.Future.html) crate was the original implementation of the type. To enable the `async/await` syntax, the core Future trait was moved into Rust’s standard library and became `std::future::Future`. In some sense, the `std::future::Future` can be seen as a minimal subset of `futures::future::Future`.
-
-It is critical to understand the difference between `std::future::Future` and `futures::future::Future`, and the approach that `async-std` takes towards them. In itself, `std::future::Future` is not something you want to interact with as a user—except by calling `.await` on it. The inner workings of `std::future::Future` are mostly of interest to people implementing `Future`. Make no mistake—this is very useful! Most of the functionality that used to be defined on `Future` itself has been moved to an extension trait called [`FutureExt`](https://docs.rs/futures/0.3/futures/future/trait.FutureExt.html). From this information, you might be able to infer that the `futures` library serves as an extension to the core Rust async features.
-
-In the same tradition as `futures`, `async-std` re-exports the core `std::future::Future` type. You can actively opt into the extensions provided by the `futures` crate by adding it to your `Cargo.toml` and importing `FutureExt`.
-
-## Interfaces and Stability
-
- `async-std` aims to be a stable and reliable library, at the level of the Rust standard library. This also means that we don't rely on the `futures` library for our interface. Yet, we appreciate that many users have come to like the conveniences that `futures-rs` brings. For that reason, `async-std` implements all `futures` traits for its types.
- 
- Luckily, the approach from above gives you full flexibility. If you care about stability a lot, you can just use `async-std` as is. If you prefer the `futures` library interfaces, you link those in. Both uses are first class.
-
-## `async_std::future`
-
-There’s some support functions that we see as important for working with futures of any kind. These can be found in the `async_std::future` module and are covered by our stability guarantees.
-
-## Streams and Read/Write/Seek/BufRead traits
-
-Due to limitations of the Rust compiler, those are currently implemented in `async_std`, but cannot be implemented by users themselves.