// ownership in practice: a list owns its boxes. nothing here calls free;
// everything is released at the end of the block that owns it.
.u box(v) { let b = new(1); b[0] = v; return u*b; }
.u mklist(cap) { let l = new(cap + 1); l[0] = 0; return u*l; }
// item m*arrives (it was given down), and goes d*on into the borrowed list
fn push(.m l, .d item) { l[l[0] + 1] = d*item; l[0] = l[0] + 1; return 0; }
fn show(.m l) {
	let i = 1;
	put_c('[');
	while (i <= l[0]) { if (i > 1) put_c(' '); put_n(l[i][0]); i++; }
	put_c(']');
	return 0;
}
.u squares(n) {
	let l = mklist(n), i = 0;
	while (i < n) {
		let b = box(i * i);
		push(l, d*b);
		i++;
	}
	return u*l;
}
fn main() {
	let before = live_objects();
	{
		let l = squares(6);
		show(l); put_c(10);
		put_s("live: "); put_n(live_objects() - before); put_c(10);
	}
	put_s("after the block: "); put_n(live_objects() - before); put_c(10);
	return 0;
}