1 files changed, 38 insertions, 0 deletions
diff --git a/docs/history/15-o3/code/examples/life.zc b/docs/history/15-o3/code/examples/life.zc
new file mode 100644
index 0000000..a43d660
--- /dev/null
+++ b/docs/history/15-o3/code/examples/life.zc
@@ -0,0 +1,38 @@
+// conway's life on a 10 x 20 torus, with typed 2d arrays in a struct.
+// a glider walks diagonally and wraps around the edges.
+const H = 10, W = 20;
+struct board { [10][20]int c; };
+
+int get(*board b, int y, int x) { return b.c[(y + H) % H][(x + W) % W]; }
+fn step(*board from, *board to)
+{
+	for (int y = 0; y < H; y++)
+		for (int x = 0; x < W; x++) {
+			int n = 0;
+			for (int dy = 0 - 1; dy <= 1; dy++)
+				for (int dx = 0 - 1; dx <= 1; dx++)
+					if (dy || dx) n += get(from, y + dy, x + dx);
+			to.c[y][x] = n == 3 || (n == 2 && from.c[y][x]);
+		}
+	return 0;
+}
+fn show(*board b, int gen)
+{
+	puts("generation "); putn(gen); putc(10);
+	for (int y = 0; y < H; y++) { for (int x = 0; x < W; x++) putc(b.c[y][x] ? '#' : '.'); putc(10); }
+	return 0;
+}
+fn main()
+{
+	*board a = new(board), b = new(board);
+	a.c[0][1] = 1; a.c[1][2] = 1; a.c[2][0] = 1; a.c[2][1] = 1; a.c[2][2] = 1;
+	// two generations a pass, a -> b -> a: owned boards can't be swapped
+	// through a temporary, since the analyzer can't follow that
+	for (int g = 0; g <= 40; g += 2) {
+		if (g % 20 == 0) show(a, g);
+		step(a, b);
+		step(b, a);
+	}
+	free(d*a); free(d*b);
+	return 0;
+}