Effective Kotlin
Effective Kotlin
Best practices
About the Book
Kotlin is a powerful and pragmatic language, but it's not enough to know about its features. We also need to know when they should be used and in what way. This book is a guide for Kotlin developers on how to become excellent Kotlin developers. It presents and explains in-depth the best practices for Kotlin development. Each item is presented as a clear rule of thumb, supported by detailed explanations and practical examples.
If you are interested in paperback, you can purchase it here.
About the Author
Bundles that include this book
Reader Testimonials
Rafał Kuźmiński
Well done! I've read a few items and I have to admit that I learned some interesting stuff. Great book :)
Hanno Günther
Really love this book! 😍
Hubert Kosacki
Some time ago I started reading @EffectiveKotlin by @marcinmoskala, it's a must-read for every developer writing Kotlin. Even if you don't agree with all the items, for sure it will make you think twice about what you're coding.
Archie David
Thanks for writing Effective Kotlin, I'm liking the tips from the book so far.
Andy Gibel
I really enjoyed your Effective Kotlin book and intend to use it for an "Advanced Kotlin" workshop series I'm planning at work
Table of Contents
- Part 1: Good code
-
Chapter 1: Safety
- Item 1: Limit mutability
- Item 2: Minimize the scope of variables
- Item 3: Eliminate platform types as soon as possible
- Item 4: Do not expose inferred types
- Item 5: Specify your expectations on arguments and state
- Item 6: Prefer standard errors to custom ones
-
Item 7: Prefer
nullorFailureresult when the lack of result is possible - Item 8: Handle nulls properly
-
Item 9: Close resources with
use - Item 10: Write unit tests
-
Chapter 2: Readability
- Item 11: Design for readability
- Item 12: Operator meaning should be consistent with its function name
-
Item 13: Avoid returning or operating on
Unit? - Item 14: Specify the variable type when it is not clear
- Item 15: Consider referencing receivers explicitly
- Item 16: Properties should represent state, not behavior
- Item 17: Consider naming arguments
- Item 18: Respect coding conventions
- Item 14: Specify the variable type when it is not clear
- Item 15: Consider referencing receivers explicitly
- Item 16: Properties should represent state, not behavior
- Item 17: Consider naming arguments
- Item 18: Respect coding conventions
- Part 2: Code design
-
Chapter 3: Reusability
- Item 19: Do not repeat knowledge
- Item 20: Do not repeat common algorithms
- Item 21: Use property delegation to extract common property patterns
- Item 22: Use generics when implementing common algorithms
- Item 23: Avoid shadowing type parameters
- Item 24: Consider variance for generic types
- Item 25: Reuse between different platforms by extracting common modules
-
Chapter 4: Abstraction design
- Item 26: Each function should be written in terms of a single level of abstraction
- Item 27: Use abstraction to protect code against changes
- Item 28: Specify API stability
- Item 29: Consider wrapping external API
- Item 30: Minimize elements visibility
- Item 31: Define contract with documentation
- Item 32: Respect abstraction contracts
-
Chapter 5: Object creation
- Item 33: Consider factory functions instead of secondary constructors
- Item 34: Consider a primary constructor with named optional arguments
- Item 35: Consider defining a DSL for complex object creation
-
Chapter 6: Class design
- Item 36: Prefer composition over inheritance
- Item 37: Use the data modifier to represent a bundle of data
- Item 38: Use function types or functional interfaces to pass operations and actions
- Item 39: Use sealed classes and interfaces to express restricted hierarchies
- Item 40: Prefer class hierarchies instead of tagged classes
- Item 41: Use enum to represent a list of values
-
Item 42: Respect the contract of
equals -
Item 43: Respect the contract of
hashCode -
Item 44: Respect the contract of
compareTo - Item 45: Consider extracting non-essential parts of your API into extensions
- Item 46: Avoid member extensions
- Part 3: Efficiency
-
Chapter 7: Make it cheap
- Item 47: Avoid unnecessary object creation
- Item 48: Use the inline modifier for functions with parameters of functional types
- Item 49: Consider using inline value classes
- Item 50: Eliminate obsolete object references
-
Chapter 8: Efficient collection processing
- Item 51: Prefer Sequences for big collections with more than one processing step
- Item 52: Consider associating elements to a map
- Item 53: Consider using groupingBy instead of groupBy
- Item 54: Limit the number of operations
- Item 55: Consider Arrays with primitives for performance-critical processing
- Item 56: Consider using mutable collections
- Dictionary
- Notes
The Leanpub 60-day 100% Happiness Guarantee
Within 60 days of purchase you can get a 100% refund on any Leanpub purchase, in two clicks.
See full terms
Do Well. Do Good.
Authors have earned$11,590,330writing, publishing and selling on Leanpub, earning 80% royalties while saving up to 25 million pounds of CO2 and up to 46,000 trees.
Learn more about writing on Leanpub
Free Updates. DRM Free.
If you buy a Leanpub book, you get free updates for as long as the author updates the book! Many authors use Leanpub to publish their books in-progress, while they are writing them. All readers get free updates, regardless of when they bought the book or how much they paid (including free).
Most Leanpub books are available in PDF (for computers), EPUB (for phones and tablets) and MOBI (for Kindle). The formats that a book includes are shown at the top right corner of this page.
Finally, Leanpub books don't have any DRM copy-protection nonsense, so you can easily read them on any supported device.
Learn more about Leanpub's ebook formats and where to read them
Top Books
- #1
SignalR on .NET 6 - the Complete Guide
Fiodar SazanavetsLearn everything there is to learn about SignalR and how to integrate it with the latest .NET 6 and C# 10 features. Learn how to connect any type of client to SignalR, including plain WebSocket client. Learn how to build interactive applications that can communicate with each other in real time without making excessive calls.
- #2
The easiest way to learn design patterns
Fiodar SazanavetsLearn design patterns in the easiest way possible. You will no longer have to brute-force your way through each one of them while trying to figure out how it works. The book provides a unique methodology that will make your understanding of design patterns stick. It can also be used as a reference book where you can find design patterns in seconds.
- #3
Functional event-driven architecture: Powered by Scala 3
Gabriel VolpeExplore the event-driven architecture (EDA) in a purely functional way, mainly powered by Fs2 streams in Scala 3!
Leverage your functional programming skills by designing and writing stateless microservices that scale, powered by stateful message brokers.
- #4
C++20 - The Complete Guide
Nicolai M. JosuttisAll the new language and library features of C++20 (for those who know previous versions).
The book presents all new language and library features of C++20. Learn how this impacts day-to-day programming, to benefit in practice, to combine new features, and to avoid all new traps.
Buy early, pay less, free updates.
Other books:
- #5
Jetpack Compose internals
Jorge CastilloJetpack Compose is the future of Android UI. Master how it works internally and become a more efficient developer with it. You'll also find it valuable if you are not an Android dev. This book provides all the details to understand how the Compose compiler & runtime work, and how to create a client library using them.
- #6
Ansible for DevOps
Jeff GeerlingAnsible is a simple, but powerful, server and configuration management tool. Learn to use Ansible effectively, whether you manage one server—or thousands.
- #7
OpenIntro Statistics
David Diez, Christopher Barr, Mine Cetinkaya-Rundel, and OpenIntroA complete foundation for Statistics, also serving as a foundation for Data Science.
Leanpub revenue supports OpenIntro (US-based nonprofit) so we can provide free desk copies to teachers interested in using OpenIntro Statistics in the classroom and expand the project to support free textbooks in other subjects.
More resources: openintro.org.
- #8
R Programming for Data Science
Roger D. PengThis book brings the fundamentals of R programming to you, using the same material developed as part of the industry-leading Johns Hopkins Data Science Specialization. The skills taught in this book will lay the foundation for you to begin your journey learning data science. Printed copies of this book are available through Lulu.
- #9
CCIE Service Provider Version 4 Written and Lab Exam Comprehensive Guide
Nicholas RussoThe service provider landscape has changed rapidly over the past several years. Networking vendors are continuing to propose new standards, techniques, and procedures for overcoming new challenges while concurrently reducing costs and delivering new services. Cisco has recently updated the CCIE Service Provider track to reflect these changes; this book represents the author's personal journey in achieving that certification.
- #10
CCIE SP v5.0
Łukasz Bromirski, Piotr Jablonski, and Nicholas RussoAre you striving to prepare to and pass CCIE SP lab exam? Take the opportunity and get this workbook! With the attached initial cfg files you will prepare yourself for the CCIE SP exam as well as learn SP technologies applicable to all kinds of today modern networks! This workbook covers blueprint topics and provides challenging examples.
Top Bundles
- #1
Practical FP in Scala + Functional event-driven architecture
2 Books
Practical FP in Scala (A hands-on approach) & Functional event-driven architecture, aka FEDA, (Powered by Scala 3), together as a bundle! The content of PFP in Scala is a requirement to understand FEDA so why not take advantage of this bundle!? - #2
Software Architecture for Developers: Volumes 1 & 2 - Technical leadership and communication
2 Books
"Software Architecture for Developers" is a practical and pragmatic guide to modern, lightweight software architecture, specifically aimed at developers. You'll learn:The essence of software architecture.Why the software architecture role should include coding, coaching and collaboration.The things that you really need to think about before... - #3
All the Books of The Medical Futurist
6 Books
We put together the most popular books from The Medical Futurist to provide a clear picture about the major trends shaping the future of medicine and healthcare. Digital health technologies, artificial intelligence, the future of 20 medical specialties, big pharma, data privacy, digital health investments and how technology giants such as Amazon... - #4
CCIE Service Provider Ultimate Study Bundle
2 Books
Piotr Jablonski, Lukasz Bromirski, and Nick Russo have joined forces to deliver the only CCIE Service Provider training resource you'll ever need. This bundle contains a detailed and challenging collection of workbook labs, plus an extensively detailed technical reference guide. All of us have earned the CCIE Service Provider certification... - #6
Pattern-Oriented Memory Forensics and Malware Detection
2 Books
This training bundle for security engineers and researchers, malware and memory forensics analysts includes two accelerated training courses for Windows memory dump analysis using WinDbg. It is also useful for technical support and escalation engineers who analyze memory dumps from complex software environments and need to check for possible... - #7
Modern C++ Collection
3 Books
Get All about Modern C++C++ Standard Library, including C++20Concurrency with Modern C++, including C++20C++20Each book has about 200 complete code examples. Updates are included. When I update one of the books, you immediately get the updated bundle. You can expect significant updates to each new C++ standard (C++23, C++26, .. ) and also... - #9
Linux Administration Complet
4 Books
Ce lot comprend les quatre volumes du Guide Linux Administration :Linux Administration, Volume 1, Administration fondamentale : Guide pratique de préparation aux examens de certification LPIC 1, Linux Essentials, RHCSA et LFCS. Administration fondamentale. Introduction à Linux. Le Shell. Traitement du texte. Arborescence de fichiers. Sécurité...
