Secondly, there is async iteration which is already pretty good syntax wise.
I agree async iteration is pretty good - the `Chan` class implements both `Iterable` and `AsyncIterable`.
For quite a few scenarios, async generators are a better choice. They do have limitations, however. For example, you _can_ implement fan-in, but there's no easy mechanism to fan-in in a blocking manner, from sources that aren't known ahead of time. It's also hard to implement a "fair" mechanism, that doesn't bias certain inputs (like you might desire if multiplexing logs, for example).
I still like "pipelining" over that, but that can also be implemented with just an iterator, pretty trivially.