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 apply function


apply is a function that applies a function to a list of arguments.

Unfortunately, Swift does not provide any apply method on arrays. To be able to implement Applicative Functors, we need to develop the apply function. The following code presents a simple version of the apply function with only one argument:

func apply<T, V>(fn: ([T]) -> V, args: [T]) -> V { 
    return fn(args) 
} 

The apply function takes a function and an array of any type and applies the function to the first element of the array. Let's test this function as follows:

let numbers = [1, 3, 5] 

func incrementValues(a: [Int]) -> [Int] { 
    return a.map { $0 + 1 } 
} 

let applied = apply(fn: incrementValues, args: numbers)