Book Image

Functional Kotlin

Book Image

Functional Kotlin

Overview of this book

Functional programming makes your application faster, improves performance, and increases your productivity. Kotlin supports many of the popular and advanced functional features of functional languages. This book will cover the A-Z of functional programming in Kotlin. This book bridges the language gap for Kotlin developers by showing you how to create and consume functional constructs in Kotlin. We also bridge the domain gap by showing how functional constructs can be applied in business scenarios. We’ll take you through lambdas, pattern matching, immutability, and help you develop a deep understanding of the concepts and practices of functional programming. If you want learn to address problems using Recursion, Koltin has support for it as well. You’ll also learn how to use the funKtionale library to perform currying and lazy programming and more. Finally, you’ll learn functional design patterns and techniques that will make you a better programmer.By the end of the book, you will be more confident in your functional programming skills and will be able to apply them while programming in Kotlin.
Table of Contents (22 chapters)
Title Page
Copyright and Credits
Dedication
Packt Upsell
Contributors
Preface
Index

Primitive streams


Primitive streams were introduced in Java 8, to take advantage of primitive data types in Java while using Streams (again, Streams are basically from Java, and Kotlin just adds a few extension functions to the Streams API). IntStream, LongStream, and DoubleStream are part of those primitive Streams.

These primitive streams work similarly to the normal Stream with some added features of the primitive data types.

So, let's take an example; have a look at the following program:

  fun main(args: Array<String>) { 
      val intStream = IntStream.range(1,10) 
      val result = intStream.sum() 
      println("The sum of elements is $result") 
  } 

So, we created an IntStream value with the IntStream.range() function, the range function takes two integers as the starting and ending point and creates a Stream ranging from the specified integers, with both included. We then calculated the sum and printed it. The program seems quite easy, and credit goes to IntStream obviously...