Mastering Rust - Second Edition

Futures

Juggling with mio's socket polling state machine is not very convenient. To provide a higher-level API that can be used by application developers, we have the futures crate. The futures crate provides a trait named Future, which is the core component of the crate. A future represents the idea of a computation that is not immediately available, but might be available later. Let's look at its type signature of the Future trait to get more information about it:

pub trait Future {    type Item;    type Error;    fn poll(&mut self) -> Poll<Self::Item, Self::Error>;}

A Future is an associated type trait that defines two types: an Item type representing the value that the Future will resolve to and an Error type that specifies what error type the ...