Book Image

Learning Functional Programming in Go

By : Lex Sheehan
Book Image

Learning Functional Programming in Go

By: Lex Sheehan

Overview of this book

Lex Sheehan begins slowly, using easy-to-understand illustrations and working Go code to teach core functional programming (FP) principles such as referential transparency, laziness, recursion, currying, and chaining continuations. This book is a tutorial for programmers looking to learn FP and apply it to write better code. Lex guides readers from basic techniques to advanced topics in a logical, concise, and clear progression. The book is divided into four modules. The first module explains the functional style of programming: pure functional programming, manipulating collections, and using higher-order functions. In the second module, you will learn design patterns that you can use to build FP-style applications. In the next module, you will learn FP techniques that you can use to improve your API signatures, increase performance, and build better cloud-native applications. The last module covers Category Theory, Functors, Monoids, Monads, Type classes and Generics. By the end of the book, you will be adept at building applications the FP way.
Table of Contents (21 chapters)
Title Page
Credits
About the Author
Acknowledgments
About the Reviewer
www.PacktPub.com
Customer Feedback
Preface
Index

If Go had generics


If Go had generics, we could have written a function signature like the following to replace strings with runes, and we would not have to rewrite the inner logic:

func Map(f func(v <string>) <bool>, vs [] <string>) []<bool> 

However, Go does not have generics, so we can use empty interfaces and reflection to achieve the same result.

Map function

Let's create a Map function to transform the contents of a Collection.

First, let's define Object to be the empty interface type and create a Collection type to be a slice of objects:

package main
import "fmt"
type Object interface{}
type Collection []Object
func NewCollection(size int) Collection {
     return make(Collection, size)
}

The NewCollection function creates a new instance of the collection with the given size:

type Callback func(current, currentKey, src Object) Object

The Callback type is a first-class function type that returns the calculated result:

func Map(c Collection, cb Callback) Collection {
...