The concept of functional reactive programming emerged by combining FP paradigms with reactive programming.

The definition of functional reactive programming says it is a programming paradigm for reactive programming (asynchronous dataflow programming) using the building blocks of FP (for example, map, reduce, and filter).

So, let's begin by defining reactive programming, and then we will discuss combining them with FP.

Reactive programming is a modern programming paradigm, which talks about propagation of change, that is, instead of representing the world as a series of states, reactive programming models behavior.

Reactive programming is an asynchronous programming paradigm that revolves around data streams and the propagation of change. In simpler words, those programs which propagate all the changes that affected its data/data streams to all the interested parties (such as end users, components and sub-parts, and other programs that are somehow related) are called reactive programs.

Reactive programming is best defined with Reactive Manifesto, as described in the following section.