blog/get-going-hello-world: second draft (#90)
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title: "Get Going: Hello, World!"
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date: 2019-10-28
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series: get-going
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tags:
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- golang
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- book
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- draft
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---
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# Get Going: Hello, World!
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This post is a draft of the first chapter in a book I'm writing to help people learn the
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[Go][go] programming language. It's aimed at people who understand the high
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level concepts of programming, but haven't had much practical experience with
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it. This is a sort of spiritual successor to my old
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[Getting Started with Go][gswg] post from 2015. A lot has changed in the
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ecosystem since then, as well as my understanding of the language.
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[go]: https://golang.org
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[gswg]: https://christine.website/blog/getting-started-with-go-2015-01-28
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Like always, feedback is very welcome. Any feedback I get will be used to help
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make this book even better.
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This article is a bit of an expanded version of what the first chapter will
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eventually be. I also plan to turn a version of this article into a workshop for
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my dayjob.
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## What is Go?
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Go is a compiled programming language made by Google. It has a lot of features
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out of the box, including:
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* A static type system
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* Fast compile times
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* Efficient code generation
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* Parallel programming for free*
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* A strong standard library
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* Cross-compilation with ease (including webassembly)
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* and more!
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\* You still have to write code that can avoid race conditions, more on those
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later.
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### Why Use Go?
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Go is a very easy to read and write programming language. Consider this snippet:
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```go
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func Add(x int, y int) int {
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return x + y
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}
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```
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This function wraps [integer
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addition](https://golang.org/ref/spec#Arithmetic_operators). When you call it it
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returns the sum of x and y.
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## Installing Go
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### Linux
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Installing Go on Linux systems is a very distribution-specific thing. Please see
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[this tutorial on
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DigitalOcean](https://www.digitalocean.com/community/tutorials/how-to-install-go-on-ubuntu-18-04)
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for more information.
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### macOS
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* Go to https://golang.org/dl
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* Download the .pkg file
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* Double-click on it and go through the installer process
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### Windows
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* Go to https://golang.org/dl
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* Download the .msi file
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* Double-click on it and go through the installer process
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### Next Steps
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These next steps are needed to set up your shell for Go programs.
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Pick a directory you want to store Go programs and downloaded source code in.
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This is called your GOPATH. This is usually the `go` folder in
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your home directory. If for some reason you want another folder for this, use
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that folder instead of `$HOME/go` below.
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#### Linux/macOS
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This next step is unfortunately shell-specific. To find out what shell you are
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using, run the following command in your terminal:
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```console
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$ env | grep SHELL
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```
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The name at the path will be the shell you are using.
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##### bash
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If you are using bash, add the following lines to your .bashrc (Linux) or
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.bash_profile (macOS):
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```
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export GOPATH=$HOME/go
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export PATH="$PATH:$GOPATH/bin"
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```
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Then reload the configuration by closing and re-opening your terminal.
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##### fish
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If you are using fish, create a file in ~/.config/fish/conf.d/go.fish with the
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following lines:
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```
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set -gx GOPATH $HOME/go
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set -gx PATH $PATH "$GOPATH/bin"
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```
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##### zsh
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If you are using zsh, add the following lines to your .zshrc:
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```
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export GOPATH=$HOME/go
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export PATH="$PATH:$GOPATH/bin"
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```
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#### Windows
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Follow the instructions
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[here](https://github.com/golang/go/wiki/SettingGOPATH#windows).
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## Installing a Text Editor
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For this book, we will be using VS Code. Download and install it
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from https://code.visualstudio.com. The default settings will let you work with
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Go code.
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## Hello, world!
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Now that everything is installed, let's test it with the classic "Hello, world!"
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program. Create a folder in your home folder `Code`. Create another folder
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inside that Code folder called `get_going` and create yet another subfolder
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called `hello`. Open a file in there with VS Code (Open Folder -> Code ->
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get_going -> hello) called `hello.go` and type in the following:
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```go
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// Command hello is your first Go program.
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package main
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import "fmt"
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func main() {
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fmt.Println("Hello, world!")
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}
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```
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This program prints "Hello, world!" and then immediately exits. Here's each of
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the parts in detail:
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```go
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// Command hello is your first go program.
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package main // Every go file must be in a package.
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// Package main is used for creating executable files.
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import "fmt" // Go doesn't implicitly import anything. You need to
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// explicitly import "fmt" for printing text to
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// standard output.
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func main() { // func main is the entrypoint of the program, or
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// where the computer starts executing your code
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fmt.Println("Hello, world!") // This prints "Hello, world!" followed by a newline
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// to standard output.
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} // This ends the main function
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```
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Now click over to the terminal at the bottom of the VS Code window and run this
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program with the following command:
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```console
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$ go run hello.go
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Hello, world!
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```
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`go run` compiles and runs the code for you, without creating a persistent binary
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file. This is a good way to run programs while you are writing them.
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To create a binary, use `go build`:
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```console
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$ go build hello.go
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$ ./hello
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Hello, world!
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```
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`go build` has the compiler create a persistent binary file and puts it in the
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same directory as you are running `go` from. Go will choose the filename of the
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binary based on the name of the .go file passed to it. These binaries are
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usually static binaries, or binaries that are safe to distribute to other
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computers without having to worry about linked libraries.
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## Exercises
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The following is a list of optional exercises that may help you understand more:
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1. Replace the "world" in "Hello, world!" with your name.
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2. Rename `hello.go` to `main.go`. Does everything still work?
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3. Read through the documentation of the [fmt][fmt] package.
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[fmt]: https://golang.org/pkg/fmt
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---
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And that about wraps it up for Lesson 1 in Go. Like I mentioned before, feedback
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on this helps a lot.
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Up next is an overview on data types such as integers, true/false booleans,
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floating-point numbers and strings.
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I plan to post the book source code on my GitHub page once I have more than one
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chapter drafted.
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Thanks and be well.
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