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

A decorator implementation


Our decorator pattern example will be runnable, so we'll put it in the main package and define a main() function.

We use the easy-metrics package for recording and displaying our metrics. It comes out of the box with a nice GUI for displaying statistics.

We also import the decorator package and preface that import with a dot (.) in order to access the identifiers in the decorator package, in the local file block without a qualifier.

The main.go file

Let's have a look at the contents of main.go:

package main

import (
"crypto/tls"
   "flag"
   "fmt"
   "io/ioutil"
   "log"
   "net/http"
   "net/url"
   "os"
   "os/signal"
   "time"
   "easy_metrics"
. "decorator"
)

const  (
host = "127.0.0.1"
protocol = "http://"
)
var (
   serverUrl string
   proxyUrl string
)

Note

This is what the imports looked like before using the init script and its aliases (and glide):import (. . .    "time"    "github.com/l3x/fp-in-go/chapter5/02_decorator/easy_metrics"    . "github.com/l3x/fp...