Most unusual/weird syntax features in non-joke languages

Like in topic - what are the weirdest or very unusual syntax features you saw in other languages than Java? Please post features only from “real” languages (no Malborge, Shakespeare etc.).

I will start with this code snippet from Haxe:


class Vec3 {

	public var x : Int;
	public var y : Int;
	public var z : Int;
	
	public function new(?x : Int, ?y : Int, ?z : Int) {
		this.x = (x == null) ? 0 : x;
		this.y = (y == null) ? 0 : y;
		this.z = (z == null) ? 0 : z;
	}
	
}

Haxe don’t support method and constructor overloading, but what we see there is something similar - in this case this method can be invoked without parameters or with 1, 2 or 3 parameters, like this:


		new Vec3(); // (0, 0, 0)
		new Vec3(1); // (1, 0, 0)
		new Vec3(1, 2); // (1, 2, 0)
		new Vec3(1, 2, 3); // (1, 2, 3)