Book Image

Kotlin Design Patterns and Best Practices - Second Edition

By : Alexey Soshin
Book Image

Kotlin Design Patterns and Best Practices - Second Edition

By: Alexey Soshin

Overview of this book

This book shows you how easy it can be to implement traditional design patterns in the modern multi-paradigm Kotlin programming language, and takes you through the new patterns and paradigms that have emerged. This second edition is updated to cover the changes introduced from Kotlin 1.2 up to 1.5 and focuses more on the idiomatic usage of coroutines, which have become a stable language feature. You'll begin by learning about the practical aspects of smarter coding in Kotlin, as well as understanding basic Kotlin syntax and the impact of design patterns on your code. The book also provides an in-depth explanation of the classical design patterns, such as Creational, Structural, and Behavioral families, before moving on to functional programming. You'll go through reactive and concurrent patterns, and finally, get to grips with coroutines and structured concurrency to write performant, extensible, and maintainable code. By the end of this Kotlin book, you'll have explored the latest trends in architecture and design patterns for microservices. You’ll also understand the tradeoffs when choosing between different architectures and make informed decisions.
Table of Contents (17 chapters)
1
Section 1: Classical Patterns
6
Section 2: Reactive and Concurrent Patterns
11
Section 3: Practical Application of Design Patterns

Using expressions instead of statements

A statement is a block of code that doesn't return anything. An expression, on the other hand, returns a new value. Since statements produce no results, the only way for them to be useful is to mutate the state, whether that's changing a variable, changing a data structure, or performing some kind of IO.

Functional programming tries to avoid mutating the state as much as possible. Theoretically, the more we rely on expressions, the more our functions will be pure, with all the benefits of functional purity.

We've used the if expression many times already, so one of its benefits should be clear: it's less verbose and, for that reason, less error-prone than the if statement from other languages.

Pattern matching

The concept of pattern matching will seem like switch/case on steroids. We've already seen how the when expression can be used, which we explored in Chapter 1, Getting Started with Kotlin, so let&apos...