Book Image

Swift Functional Programming - Second Edition

By : Dr. Fatih Nayebi
Book Image

Swift Functional Programming - Second Edition

By: Dr. Fatih Nayebi

Overview of this book

Swift is a multi-paradigm programming language enabling you to tackle different problems in various ways. Understanding each paradigm and knowing when and how to utilize and combine them can lead to a better code base. Functional programming (FP) is an important paradigm that empowers us with declarative development and makes applications more suitable for testing, as well as performant and elegant. This book aims to simplify the FP paradigms, making them easily understandable and usable, by showing you how to solve many of your day-to-day development problems using Swift FP. It starts with the basics of FP, and you will go through all the core concepts of Swift and the building blocks of FP. You will also go through important aspects, such as function composition and currying, custom operator definition, monads, functors, applicative functors,memoization, lenses, algebraic data types, type erasure, functional data structures, functional reactive programming (FRP), and protocol-oriented programming(POP). You will then learn to combine those techniques to develop a fully functional iOS application from scratch
Table of Contents (19 chapters)
Title Page
Credits
About the Author
About the Reviewer
www.PacktPub.com
Customer Feedback
Dedication
Preface

Type erasure


In Chapter 3, Types and Type Casting we talked about Abstract versus Concrete types. Type erasure is a process to make abstract types such as Generics concrete.

Why we would want to do it? The answer is because we want to write code against contracts; in other words, we want to prefer composition over inheritance. Also, sometimes we would want to be more flexible with the types. This concept may sound complicated, so let's continue our example from the previous section to understand why and how we would create type-erased structures.

First, we want to examine if we can use CustomView type and create an array with CustomView elements. We will create a CustomView:

struct CustomDisabledButton: CustomView { 
    typealias ViewType = Button 
    func configure(view with: ViewType) { 
        // configure the view 
        print("Disabled button") 
    } 
} 

So far, we've created two CustomViews; the first one represents a custom enabled button and the second one represents a disabled...