1.3 Some Go Syntax

Function Declaration

A function declaration consists of the keyword func, the name of the function, a parameter list (empty for main), a result list (also empty here), and the body of the function—the statements that define what it does—enclosed in braces. We’ll take a closer look at functions in Chapter 5.

Go Syntax

Go does not require semicolons at the ends of statements or declarations, except where two or more appear on the same line. In effect, newlines following certain tokens are converted into semicolons, so where newlines are placed matters to proper parsing of Go code. For instance, the opening brace ‘{’ of the function must be on the same line as the end of the func declara- tion, not on a line by itself, and in the expression ‘x + y’, a newline is permitted after but not before the ‘+’ operator.

gofmt Tool

Go takes a strong stance on code formatting. The gofmt tool rewrites code into the standard format, and the go tool’s fmt subcommand applies gofmt to all the files in the specified package, or the ones in the current directory by default. All Go source files in the book have been run through gofmt, and you should get into the habit of doing the same for your own code. Declaring a standard format by fiat eliminates a lot of pointless debate about trivia and, more importantly, enables a variety of automated source code transformations that would be infeasible if arbitrary formatting were allowed.

Many text editors can be configured to run gofmt each time you save a file, so that your source code is always properly formatted.

goimports Tool

A related tool, goimports, additionally manages the insertion and removal of import declarations as needed. It is not part of the standard distribution but you can obtain it with this command:

$ go get golang.org/x/tools/cmd/goimports

For most users, the usual way to download and build packages, run their tests, show their documentation, and so on, is with the go tool, which we’ll look at in Section 10.7.