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

Dealing with Optionals' functionally


We have covered different approaches and tools to deal with Optionals so far. Let's examine if we can use functional programming paradigms to simplify the process.

Optional mapping

Mapping over an array would generate one element for each element in the array. Can we map over an optional to generate non-optional values? If we have some, map it; otherwise, return none. Let's examine the following code:

func mapOptionals<T, V>(transform: (T) -> V, input: T?) -> V? { 
    switch input { 
    case .some(let value): return transform(value) 
    case .none: return .none 
    } 
} 

Our input variable is a generic optional and we have a transform function that takes input and transforms it into a generic type. The result will be a generic optional type. In the function body, we use pattern matching to return the respective values. Let's test this function:

class User { 
    var name: String? 
} 

We create a class named User with an optional variable. We...