Reactive Extensions for C++.

The ReactiveX Observable model allows you to treat streams of
asynchronous events with the same sort of simple, composable
operations that you use for collections of data items like arrays.
It frees you from tangled webs of callbacks, and thereby makes
your code more readable and less prone to bugs.

The Reactive Extensions for C++ (RxCpp) is a library of algorithms
for values-distributed-in-time. The Range-v3 library does the same
for values-distributed-in-space.