Global Variables

Global variables are declared at top-level. They may be private (no pub) or public (pub). Use var for mutable globals, const for immutable globals, and extern to declare symbols provided externally (no initializer).

// public globals
pub var  NAME: OptionalType = Value;
pub const NAME: OptionalType = Value;
pub extern NAME: Type; // public external symbol (no initializer)

// private globals
var  NAME: OptionalType = Value;
const NAME: OptionalType = Value;
extern NAME: Type; // private external symbol (no initializer)

var: mutable global (initializer optional; zero-initialized if omitted).
const: immutable global (must be initialized at declaration).
extern: declares a symbol provided by the runtime/linker.

Examples:

const MY_VAL = 10;                  // private immutable global
pub var MY_VAR = 10;               // public mutable global
var COUNTER: int;                   // private mutable global, zero-initialized
pub const MAX: int = 100;           // explicit type
pub const VERSION: char* = "1.0";

pub extern stdin: void*;            // public external symbol
extern errno: int;                  // private external symbol

Reassignment rules:

pub const PI = 3.14159;
PI = 3.14; // ❌ cannot assign to const variable

pub var CONFIG = 0;
CONFIG = 1; // ✅ allowed

Local Variables

Local variables inside functions are declared using var or const.

var name: OptionalType = Value;
const name: OptionalType = Value;

Examples:

fn main() {
    var a = 10;    // mutable
    const b = 20;  // immutable
    var c: int;    // zero-initialized; defaults to 0
}

Zero Initialization

Variables (both globals and locals) declared without an initializer are automatically zero-initialized:

var x: int;
var y: float64;

printf("%d\n", x);   // prints 0
printf("%f\n", y);   // prints 0.0

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