// Structs: records with fields, passed and returned by value.
Point :: struct {
    x: s32;
    y: s32;
}

Rectangle :: struct {
    origin: Point;
    width: s32;
    height: s32;
}

Area :: (shape: Rectangle) -> s32 {
    return shape.width * shape.height;
}

Grow :: (shape: Rectangle, amount: s32) -> Rectangle {
    grown := shape;
    grown.width += amount;
    grown.height += amount;
    return grown;
}

main :: () {
    corner := Point.{x = 3, y = 4};
    print("point: (%, %)\n", corner.x, corner.y);

    box := Rectangle.{origin = corner, width = 10, height = 5};
    print("area: %\n", Area(box));

    box = Grow(box, 2);
    print("grown: %x% with area %\n", box.width, box.height, Area(box));

    copy := box;
    copy.width = 1;
    print("the copy is % wide, the original still %\n", copy.width, box.width);
}