1 files changed, 52 insertions, 0 deletions
diff --git a/docs/history/10-zc/code/tests/umd.zc b/docs/history/10-zc/code/tests/umd.zc
new file mode 100644
index 0000000..7d1bffc
--- /dev/null
+++ b/docs/history/10-zc/code/tests/umd.zc
@@ -0,0 +1,52 @@
+// lists as [len, items...], items owned by the list
+fn mklist(n) -> u
+{
+	var l = new(n + 1);
+	l[0] = 0;
+	return l as u;
+}
+fn push(m l, d item) { l[l[0] + 1] = item as d; l[0] = l[0] + 1; return 0; }
+fn sum(m l) { var s = 0, i = 1; while (i <= l[0]) { s += l[i][0]; i++; } return s; }
+fn box(v) -> u { var b = new(1); b[0] = v; return b as u; }
+fn consume(d b) { return b[0]; }
+
+fn main()
+{
+	var base = live_objects();
+	{
+		var l = mklist(8);		// u from mklist arrives here as m
+		var i = 0;
+		while (i < 5) {
+			var b = box(i * 10);	// m in the loop body
+			b as d;			// give it down
+			push(l, b);
+			i++;
+		}
+		putn(sum(l)); putc(' ');
+		putn(live_objects() - base); putc(' ');	// list + 5 boxes
+	}
+	putn(live_objects() - base); putc(' ');	// freed at the block's end, children too
+
+	// u handed up one block by assignment, and as a block value
+	var outer;
+	{
+		var t = box(7);
+		t as u;
+		outer = t;
+	}
+	var v = { var w = box(8); w as u };
+	putn(outer[0] + v[0]); putc(' ');
+
+	// d given away to a callee
+	var g = box(99);
+	putn(consume(g as d)); putc(' ');
+
+	// containers: child takes its parent's tag
+	var p = new(2), c = new(1);
+	c[0] = 5;
+	p[0] = c;
+	p[1] = new(3);
+	putn(p[0][0]); putc(' ');
+	putn(live_objects() - base); putc(10);
+	return 0;
+}