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Functional Kotlin

You're reading from   Functional Kotlin Extend your OOP skills and implement Functional techniques in Kotlin and Arrow

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Product type Paperback
Published in Feb 2018
Publisher Packt
ISBN-13 9781788476485
Length 350 pages
Edition 1st Edition
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Authors (2):
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Mario Arias Mario Arias
Author Profile Icon Mario Arias
Mario Arias
Rivu Chakraborty Rivu Chakraborty
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Rivu Chakraborty
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Table of Contents (16) Chapters Close

Preface 1. Kotlin – Data Types, Objects, and Classes FREE CHAPTER 2. Getting Started with Functional Programming 3. Immutability - It's Important 4. Functions, Function Types, and Side Effects 5. More on Functions 6. Delegates in Kotlin 7. Asynchronous Programming with Coroutines 8. Collections and Data Operations in Kotlin 9. Functional Programming and Reactive Programming 10. Functors, Applicatives, and Monads 11. Working with Streams in Kotlin 12. Getting Started with Arrow 13. Arrow Types 14. Kotlin's Quick Start 15. Other Books You May Enjoy

Single-expression functions

Until now, all our examples were declared in a normal way.

The function sum takes two Int values and adds them. Declared in a normal way, we must provide a body with curly braces and an explicit return:

fun sum(a:Int, b:Int): Int {
return a + b
}

Our sum function has its body declared inside curly braces with a return clause. But if our function is just one expression, it could have been written in a single line:

fun sum(a:Int, b:Int): Int = a + b

So, no curly braces, no return clause, and an equals (=) symbol. If you pay attention, it just looks similar to a lambda. 

If you want to cut even more characters, you can use type inference too:

fun sum(a:Int, b:Int) = a + b
Use type inference for a function's return when it is very evident which type you are trying to return. A good rule of thumb is to use it for simple...
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