.GO

Introduction

A .go file holds source code in Go, the compiled language created at Google. The go command builds all the .go files in a folder together as one package, and a go.mod file at the top of a project names the module and the versions of its dependencies.

Files whose names end in _test.go hold tests and are only compiled by go test.

Structure

A Go source file is plain UTF-8 text. It must start, after any comments, with a package clause naming its package; every file in a folder belongs to the same package, and a program’s entry point is the main function of package main. Then come the import declarations and the file’s functions, types, constants and variables.

A //go:build line before the package clause limits the file to certain systems or build tags. Layout is standardised by the gofmt tool, which indents with tabs, so most Go code looks the same.

package main

import "fmt"

func main() {
	fmt.Println("Hello, world")
}

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