Skip to main content

Function Calls

This page describes argument passing rules for function and method calls in Zynx.

Positional and Keyword Arguments​

Zynx supports positional arguments and keyword (named) arguments.

Rules:

  • You may use only positional arguments.
  • You may mix positional and keyword arguments.
  • If mixed, positional arguments must come first.
  • Keyword arguments must follow parameter order (no reordering).

Examples:

fn sum(a: i32, b: i32, c: i32 = 0) -> i32 {
    return a + b + c;
}

let x = sum(1, 2);          // positional only
let y = sum(1, b: 2, c: 3); // positional -> keyword
let z = sum(a: 1, b: 2);    // keyword only, ordered

Invalid:

sum(a: 1, 2);      // positional after keyword
sum(c: 3, a: 1);   // keyword reordering

Default Parameters​

Parameters may provide default values.

fn pick(a: i32 = 1, b: i32 = 2) -> i32 {
    return a + b;
}

let p1 = pick();          // 3
let p2 = pick(a: 3);      // 5
let p3 = pick(a: 3, b: 4); // 7

When a parameter is omitted, its default value is used.