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async_futures.txt (624B)

      1 # Coroutines and async/await
      2 
      3 These two signatures are functionally equivalent — `async fn` is just syntactic
      4 sugar that the compiler desugars into the explicit `impl Future` form.
      5 
      6 ```rust
      7 trait T {
      8   async fn f(&self) -> u32;
      9 }
     10 ```
     11 
     12 ```rust
     13 trait T {
     14   fn f(&self) -> impl Future<Output = u32>;
     15 }
     16 ```
     17 
     18 Similar to how JavaScript rewrites an await function into a normal function with
     19 promises, when you write this in Rust:
     20 
     21 ```rust
     22 async fn run() -> () {...}
     23 ```
     24 
     25 It becomes:
     26 
     27 ```rust
     28 Fn run() -> impl Future<Ouput = ()>
     29 ```
     30 
     31 The Rust futures we use today have a lot in common with how `async/await` works
     32 in JavaScript.