// struct methods, closures and ownership in one file, written so the
// compiler's hints have something to say about it. it runs as it is.

struct point {
	let x, y;

	// methods get a hidden first parameter called this
	fn dist(other) {
		let dx = this.x - other.x;
		let dy = this.y - other.y;
		return dx * dx + dy * dy;
	}
}

fn sink(.d p) { free(d*p); return 0; }

fn features() {
	// a closure copies the variables it uses when it is made
	let base = 100;
	let add = fn(a, b) { return a + b + base; };
	let total = add(10, 20);

	let p1 = new(point);
	p1.x = 5; p1.y = 12;
	let p2 = new(point);
	p2.x = 0; p2.y = 0;

	// made and given away on the next line, so it never needed a name
	let tmp = new(2);
	sink(d*tmp);

	// allocated again on every pass of the loop
	let i = 0;
	while (i < 3) {
		let scratch = new(10);
		scratch[0] = i;
		sink(d*scratch);
		i++;
	}

	return total + p1.dist(p2);
}

fn main() {
	put_n(features()); put_c(10);
	return 0;
}