Consider adding `Observable`

[sobolevn]

This can be released as an independent library: https://github.com/ReactiveX/RxPY

[mysticfall]

As a person who's been using both of the libraries, I find the prospect of composing Observables with the fluent syntax of returns very appealing.

IMHO, this would bring the Python world a step closer to some other languages where Rx and functional operators provide a unified view.

[sobolevn]

We would need to colab with @dbrattli! I would love to help building the integration sometime soon. Considering that we now have Higher Kinded Types support, this could be benefitial for both parties in terms of common API and awesome typing support.