Go Concepts - Lexical Structure

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Internal

Source Files

Go code goes into source files. They have the .go extension.

Each source file is mandatory declared to belong to a package.

They can then optionally import code from other packages, using the import keyword.

Comments

// to the end of the line
/*
  Multiline
  line 1
  ...
  line n
*/

Whitespace

Whitespace in Go are carriage returns (u+000D), newlines (u+000A), spaces (u+0020) and tabs (u+0009).

Semicolons

TODO https://golang.org/ref/spec#Semicolons

Identifiers

Types, functions, constants, variables, interfaces.

The blank identifier "_".

Identifiers (not values) can be exported or unexported.

Lower-case letter identifiers

Upper-case letter identifiers

Operators

Expression

Operators combine operands into expressions.

Literal

String Literal

Numeric Literal

Array Literal

Slice Literal

Map Literal

Struct Literal

Statements

for

if

Keywords

range type func . .
package go . . .
defer chan import . .

Constants

Variables

Variables are always initialized to the type's zero value.


  var <var-name> <type> = <initial-value>

  var a string = "blah"


  <var-name> := <initial-value>

   a := "blah"

Variable Scopes

Package-level variable

Pass by Value vs Pass by Reference

In Go, all variables are passed by value. Even for pointer variables, since the value of the pointer is a memory address, passing pointer variables is still considered pass by value.

Pointers

Pointer variable.