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

The car functor


Let's use a functor to upgrade (and downgrade) some cars! We'll start by opening our car.go file in our functor package.

The functor package

Let's have a look at src/functor/car.go:

package functor

import (
"fmt"
   "strings"
)

type (
   Car struct {
      Make string `json:"make"`
Model string `json:"model"`
}
)

It's good practice to define our types at the top. Putting them in a type block helps to keep our code clean and tidy. Another good practice is to add JSON annotations to each field of a struct to enable easy (un)marshalling of JSON into our Car struct.

Note

If you want to omit empty fields from a struct, you can add the omitempty clause to the end of your field annotation. For example, if the Make was optional or sometimes not included and we didn't want the json created from a Car struct to include empty Make fields, our struct definition would look like this:Car struct {    Make string `json:"make"`    Model string `json:"model,omitempty"`}

Next comes our interface...