Is there a way to add extension functions to Future?

use std::future::Future;

trait FutureFunctions {
    type Output;
    fn race() {

impl<F> FutureFunctions for dyn Future<Output = F> {
    type Output = F;
    fn race() {

fn main() {
    <dyn Future::<Output = ()>>::race();

    // doesn't compile:
    // Future::<Output = ()>::race();

I just want to remove <dyn ...>. Then I'll be able to do this with my framework:

use rialight::prelude::*;

let _ = Future::race(iterable).await;

It'll use the futures crate behind

impl for T: Future?

Nope. I tried a non-dyn bound instead too, similiar to that:

impl<T, Item> FutureFunctions for T
    where T: Future<Output = Item>
    type Output = Item;

I don't think you can make this syntax work. If you want to call the function like this, why not make it a freestanding function?


1 Like

Future is not a type (since edition 2021), so it can't be used where the type is expected, including the method call syntax.