Please do an episode on Reactive Programming

[bert-laverman]

Channel

This is for "C++Weekly"

Topics

• The programming paradigm itself;

  • Push vs Pull when processing asynchronous data
  • Observers vs Enumerators
  • Callbacks vs coroutines
  • ReactiveX's Observer/Observable or project Reactor's Mono/Flux. (which is admittedly Java, but still a good reference)

• A look at alternative libraries/frameworks

Length

I think this warrants more than just 5 minutes, if only because I don't see much content about this subject in combination with C++.

[YarikTH]

It is very hard topic starting from the definition itself. And there are at least 2 flavors:

• Rx - that works exclusively with streams and ads "completed" and "failed" as a separate value channels
• FRP (Functional Reactive Programming) that originated from functional languages and consist of 2 primitives (which naming is inconsistent between libraries) - behavior and event stream.

For the first there are at least official implementation and some alternatives under development.

• https://github.com/CODIANZ/another-rxcpp
• https://github.com/victimsnino/ReactivePlusPlus

For the second I can't find any mature solution used for lots of people. All projects are either under development or abandoned.

• sodium-cxx - abandoned port of "sodium" reactive library made in Java. From writers of "Functional Reactive Programming" book.
• cpp.react - abandoned port of Scala.React for which authors wrote paper "Deprecating the Observer Pattern with Scala.React". It has great ideas and documentation if you look at legacy1 branch only that is stable state before unfinished rewrite attempt in master.
• µReact my port and rethinking of cpp.react with modern syntax and modern standards. Greatly suffers from lack of documentation (only doxygen comments in header and tests) and real usage experience.
• urp - experimental 900 lines implementation made for cppcon presentation. Not ready for production and have never intended for.

It's kinda funny that author of FRP is not happy both with the name itself and with "so called FRP libraries". https://github.com/conal/talk-2015-essence-and-origins-of-frp While his attempts to describe what he meant by FRP are so overflown with complex math terminology that mere mortal programmers can't comprehend it including myself.