Book Image

Reactive Programming in Kotlin

By : Rivu Chakraborty
Book Image

Reactive Programming in Kotlin

By: Rivu Chakraborty

Overview of this book

In today's app-driven era, when programs are asynchronous, and responsiveness is so vital, reactive programming can help you write code that's more reliable, easier to scale, and better-performing. Reactive programming is revolutionary. With this practical book, Kotlin developers will first learn how to view problems in the reactive way, and then build programs that leverage the best features of this exciting new programming paradigm. You will begin with the general concepts of Reactive programming and then gradually move on to working with asynchronous data streams. You will dive into advanced techniques such as manipulating time in data-flow, customizing operators and provider and how to use the concurrency model to control asynchronicity of code and process event handlers effectively. You will then be introduced to functional reactive programming and will learn to apply FRP in practical use cases in Kotlin. This book will also take you one step forward by introducing you to Spring 5 and Spring Boot 2 using Kotlin. By the end of the book, you will be able to build real-world applications with reactive user interfaces as well as you'll learn to implement reactive programming paradigms in Android.
Table of Contents (20 chapters)
Title Page
About the Author
About the Reviewers
Customer Feedback

flatMap, concatMap – In details

As promised in the previous chapter, now we will take a deeper dive into the flatMap and concatMap operators, as, by now, we have already gained some sort of expertise on the merge and concat operators and know the differences between them.

Let's start with the differences between flatMap and concatMap, after which, we will also discuss their ideal implementation scenarios. We will also discuss some of their variants to know them better.

In the previous chapter, we mentioned that flatMap internally uses the merge operator and concatMap internally uses the concat operator. However, what difference does that make? You just learned the differences between the merge and the concat operator, but what is the point of having two separate mapping operators based on them? So, let's start with an example. We will see an example with flatMap, and then we will try to implement the same with concatMap:

    fun main(args: Array<String>) {