Introduction

Is Go an object-oriented language? Yes and no.

Frequently asked questions, Go Authors

The Go programming language is an open source project language to make programmers more productive.

According to the website [go_web] “Go is expressive, concise, clean, and efficient”. And indeed itis. My initial interest was piqued when I read early announcements about this new language that hadbuilt-in concurreny and a C-like syntax (Erlang also has built-in concurrency, but I could never getused to its syntax). Go is a compiled statically typed language that feels like a dynamically typed,interpreted language. My go to (scripting!) language Perl has taken a back seat now that Go isaround.

The unique Go language is defined by these principles:

  • Clean and Simple
  • Go strives to keep things small and beautiful. You should be able to do a lot in only a fewlines of code.
  • Concurrent
  • Go makes it easy to “fire off” functions to be run as very lightweight threads. These threadsare called goroutines 1 in Go.
  • Channels
  • Communication with these goroutines is done, either via shared state or via channels [csp].
  • Fast
  • Compilation is fast and execution is fast. The aim is to be as fast as C. Compilation time ismeasured in seconds.
  • Safe
  • Explicit casting and strict rules when converting one type to another. Go has garbagecollection. No more free() in Go: the language takes care of this.
  • Standard format
  • A Go program can be formatted in (almost) any way the programmers want, but an official formatexists. The rule is very simple: The output of the filter gofmt is the officially endorsedformat.
  • Postfix types
  • Types are given after the variable name, thus var a int, instead of int a.
  • UTF-8
  • UTF-8 is everywhere, in strings and in the program code. Finally you can use (\Phi = \Phi + 1)in your source code.
  • Open Source
  • The Go license is completely open source.
  • Fun
  • Programming with Go should be fun!

As I mentioned Erlang also shares some features of Go. A notable difference between Erlang and Go isthat Erlang borders on being a functional language, while Go is imperative. And Erlang runs ina virtual machine, while Go is compiled.

How to Read this Book

I’ve written this book for people who already know some programming languages and how to program. Inorder to use this book, you (of course) need Go installed on your system, but you can easily tryexamples online in the Go playground2. All exercises in this book workwith Go 1, the first stable release of Go – if not, it’s a bug.

The best way to learn Go is to create your own programs. Each chapter therefore includes exercises(and answers to exercises) to acquaint you with the language. Each exercise is either easy,intermediate, or difficult. The answers are included after the exercises on a new page. Someexercises don’t have an answer; these are marked with an asterisk.

Here’s what you can expect from each chapter:

  • Chapter 2. Basics
    • We’ll look at the basic types, variables, and control structures available in the language.
  • Chapter 3. Functions
    • Here we look at functions, the basic building blocks of Go programs.
  • Chapter 4. Packages
    • We’ll see that functions and data can be grouped together in packages. We’ll also see how to document and test our packages.
  • Chapter 5. Beyond the basics
    • We’ll create our own types. We’ll also look at memory allocations in Go.
  • Chapter 6. Interfaces
    • We’ll learn how to use interfaces. Interfaces are the central concept in Go, as Go does not support object orientation in the traditional sense.
  • Chapter 7. Concurrency
    • We’ll learn the go keyword, which can be used to start function in separate routines (called goroutines). Communication with those goroutines is done via channels.
  • Chapter 8. Communication
    • Finally we’ll see how to interface with the rest of the world from within a Go program. We’ll see how to create files and read and write to and from them. We’ll also briefly look into networking.

Official Documentation

There is a substantial amount of documentation written about Go. The Go Tutorial [go_tutorial], theGo Tour (with lots of exercises) and the Effective Go [effective_go] are helpful resources. Thewebsite http://golang.org/doc/ is a very good starting point for reading up onGo3. Reading these documents is certainly notrequired, but it is recommended.

When searching on the internet use the term “golang” instead of plain “go”.

Go comes with its own documentation in the form of a program called godoc4. If you areinterested in the documentation for the built-ins, simply do this:

  1. % godoc builtin

To get the documentation of the hash package, just:

  1. % godoc hash

To read the documentation of fnv contained in hash, you’ll need to issue godoc hash/fnv asfnv is a subdirectory of hash.

  1. PACKAGE DOCUMENTATION
  3. package fnv
  4.     import "hash/fnv"
  6.     Package fnv implements FNV-1 and FNV-1a, non-cryptographic hash
  7.     ...