FRP represents an intersection of two programming paradigms.
Functional programming
Functional programming is a programming paradigm where you model everything as a result of a function that avoids changing state and mutating data.
Reactive programming
Reactive programming is the practice of programming with asynchronous data streams or event streams. An event stream can be anything like keyboard inputs, button taps, gestures, GPS location updates, accelerometer, and iBeacon. You can listen to a stream and react to it accordingly.
FRP is the combination of functional and reactive paradigms. In other words, it is reacting to data streams using the functional paradigm. FRP is not a utility or a library — it changes the way you architect your applications and the way you think about your applications.
https://www.freecodecamp.org/news/functional-reactive-programming-frp-imperative-vs-declarative-vs-reactive-style-84878272c77f/