Consider the following recursive implementation of the fibonacci numbers:
rust
async fn fib(n : u32) -> u64 {
match n {
0 => panic!("zero is not a valid argument to fib()!"),
1 | 2 => 1,
3 => 2,
_ => fib(n-1).await + fib(n-2).await
}
}
console
error[E0733]: recursion in an `async fn` requires boxing
--> src/main.rs:1:26
|
1 | async fn fib(n : u32) -> u64 {
| ^^^ recursive `async fn`
|
= note: a recursive `async fn` must be rewritten to return a boxed `dyn Future`.
This crate provides an attribute macro to automatically convert async fn f(...) -> ReturnType
to a fn f(...) -> Pin
```rust use asyncrecursion::asyncrecursion;
async fn fib(n : u32) -> u64 { match n { 0 => panic!("zero is not a valid argument to fib()!"), 1 | 2 => 1, 3 => 2, _ => fib(n-1).await + fib(n-2).await } } ```
Currently the macro doesn't consider lifetimes at all; this is something I plan to work on in the future.
Licensed under either of * Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0) * MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT) at your option.