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