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

The map function


Swift has a built-in higher-order function named map that can be used with collection types such as arrays. The map function solves the problem of transforming the elements of an array using a function. The following example presents two different approaches to transform a set of numbers:

let numbers = [10, 30, 91, 50, 100, 39, 74] 
var formattedNumbers: [String] = [] 

for number in numbers { 
    let formattedNumber = "\(number)$" 
    formattedNumbers.append(formattedNumber) 
} 

let mappedNumbers = numbers.map { "\($0)$" } 

The first approach to solve the problem is imperative and uses a for-in loop to go through the collection and transform each element in the array. This iteration technique is known as external iteration because we specify how to iterate. It requires us to explicitly access the elements sequentially from beginning to end. Also, it is required to create a variable that is mutated repeatedly while the task is performed in the loop.

This process is error...