Chapter 2. A Look at Reactive Extensions

Reactive Extensions—or Rx—is a Reactive Programming library from Microsoft to build complex asynchronous programs. It models time-varying values and events as observable sequences and is implemented by extending the Observer design pattern.

Its first target platform was .NET, but Netflix has ported Rx to the JVM under the name RxJava. Microsoft also develops and maintains a port of Rx to JavaScript called RxJS, which is the tool we used to build the sine-wave application. The two ports work a treat for us since Clojure runs on the JVM and ClojureScript in JavaScript environments.

As we saw in Chapter 1, What is Reactive Programming?, Rx is inspired by Functional Reactive Programming but uses different terminology. In FRP, the two main abstractions are behaviors and events. Although the implementation details are different, observable sequences represent events. Rx also provides a behavior-like abstraction through another data...