To get the most out of this book

The only recommended software to run and write Kotlin programs is IntelliJ IDEA (there are other ways to do it, and we cover them in the Appendix, Kotlin's Quick Start).

You can download IntelliJ IDEA from https://www.jetbrains.com/idea/download/.

You can install IntelliJ IDEA on Windows, Mac, and Linux:

• For Windows: You can use any Windows version from XP to 10. To install it on Windows, run the installer executable and follow the instructions.
• For Mac: You can use any macOS version starting from 10.8. To install it on macOS, mount the disk image file and copy IntelliJ IDEA.app60 to your Application folder.
• For Linux: You can use any GNOME or KDE desktop. To install it Linux unpack the tar.gz file using the tar -xzf idea-*.tar.gz command and run the idea.sh from the bin subdirectory.

Download the example code files

You can download the example code files for this book from your account at www.packtpub.com. If you purchased this book elsewhere, you can visit www.packtpub.com/support and register to have the files emailed directly to you.

You can download the code files by following these steps:

1. Log in or register at www.packtpub.com.
2. Select the SUPPORT tab.
3. Click on Code Downloads & Errata.
4. Enter the name of the book in the Search box and follow the onscreen instructions.

Once the file is downloaded, please make sure that you unzip or extract the folder using the latest version of:

• WinRAR/7-Zip for Windows
• Zipeg/iZip/UnRarX for Mac
• 7-Zip/PeaZip for Linux

The code bundle for the book is also hosted on GitHub at https://github.com/PacktPublishing/Functional-Kotlin. In case there's an update to the code, it will be updated on the existing GitHub repository.

We also have other code bundles from our rich catalog of books and videos available at https://github.com/PacktPublishing/. Check them out!

Download the color images

We also provide a PDF file that has color images of the screenshots/diagrams used in this book. You can download it here: https://www.packtpub.com/sites/default/files/downloads/FunctionalKotlin_ColorImages.pdf .

Conventions used

There are a number of text conventions used throughout this book.

CodeInText: Indicates code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles. Here is an example: "We introduced a new BakeryGood class, with the shared behavior and state of both Cupcake and Biscuit classes and we made both classes extend BakeryGood."

A block of code is set as follows:

open class BakeryGood(val flavour: String) { 
  fun eat(): String { 
    return "nom, nom, nom... delicious $flavour bakery good" 
  } 
} 

class Cupcake(flavour: String): BakeryGood(flavour) 
class Biscuit(flavour: String): BakeryGood(flavour)

When we wish to draw your attention to a particular part of a code block, the relevant lines or items are set in bold:

fun main(args: Array<String>) { 
    val emptyList1 = listOf<Any>()
    val emptyList2 = emptyList<Any>() 
     
    println("emptyList1.size = ${emptyList1.size}") 
    println("emptyList2.size = ${emptyList2.size}") 
} 

Any command-line input or output is written as follows:

$ kotlin HelloKt

Bold: Indicates a new term, an important word, or words that you see onscreen. For example, words in menus or dialog boxes appear in the text like this. Here is an example: "A dialog will appear that will ask whether you want to open it as a file or as a project. Click on Open As Project"

Warnings or important notes appear like this.

Tips and tricks appear like this.