Variables

A variable is a named container for a value of a specific type. Variables can be local (inside a function) or global (at top level).

Declaration

var <name> <type>

Examples:

var x int
var c char
var p *int
var a int[32]

The type is required unless an initializer allows inference (see below).

Initializers

A variable can be initialized at declaration:

var x int = 10
var c char = 'a'
var s *string = "Hello, World"
var a int[3] = [1, 2, 3]

Type inference

If the initializer determines the type unambiguously, the type may be omitted:

var x = 5                  // int
var s = "test"             // *string
var a = [1, 2, 3]          // int[3]
var a int[] = [1, 2, 3]    // int[3], unfinished -> finished declaration

Ambiguous initializers require an explicit type:

var e = []    // error: cannot infer element type

Constants

A variable with a compile-time known initializer can be declared const:

const x = 5
const y int = 10

A constant:

• Cannot be modified after declaration.
• Cannot have its address taken (&x is an error).
• May be inlined and eliminated by the optimizer.

const x = 5

&x         // error: cannot take address of a constant

Storage duration

The storage duration of a variable depends on where it is declared:

Where	Storage	Initialization
Top level	Global (static segment)	Zero-initialized
Inside a function	Local (stack)	Uninitialized unless initialized at declaration

var global int    // zero-initialized

func void main[]
    var local int    // uninitialized
end