genawaiter

This crate implements stackless generators (aka coroutines) in stable Rust. Instead of using yield, which won't be stabilized anytime soon, you use async/await, which is stable today.

Features:

• supports resume arguments and completion values
• supports async generators (e.g., Streams)
• allocation-free
• no runtime dependencies
  • no compile-time dependencies either, with default-features = false
• built on top of standard language constructs, which means there are no platform-specific shenanigans

Example:

let odd_numbers_less_than_ten = gen!({
    let mut n = 1;
    while n < 10 {
        yield_!(n); // Suspend a function at any point with a value.
        n += 2;
    }
});

// Generators can be used as ordinary iterators.
for num in odd_numbers_less_than_ten {
    println!("{}", num);
}

Result:

1
3
5
7
9

And here is the same generator, this time without macros. This is how you do things with default-features = false (which eliminates the proc macro dependencies).

let odd_numbers_less_than_ten = Gen::new(|co| async move {
    let mut n = 1;
    while n < 10 {
        co.yield_(n).await;
        n += 2;
    }
});

See the docs for more.