build: extract example executable from default target

example/main.zig

@@ -0,0 +1,53 @@
+const std = @import("std");
+
+const yaml = @import("yaml");
+
+pub fn main() !void {
+    var gpa = std.heap.GeneralPurposeAllocator(.{}){};
+    defer _ = gpa.deinit();
+    const allocator = gpa.allocator();
+
+    const slurp = std.fs.cwd().readFileAlloc(
+        allocator,
+        "test.yaml",
+        1024 * 1024 * 1024,
+    ) catch |err| {
+        std.debug.print("couldn't open test.yaml in the cwd\n", .{});
+        return err;
+    };
+    defer allocator.free(slurp);
+
+    var diag = yaml.ParseDiagnostic{ .message = "?????" };
+    const doc = yaml.Document.fromString(allocator, slurp, &diag) catch |err| {
+        std.debug.print(
+            "Failed to parse line: {d}, col: {d}: {s}\n",
+            .{ diag.line, diag.col, diag.message },
+        );
+        return err;
+    };
+    defer doc.deinit();
+
+    std.debug.print("\n-----\n\n", .{});
+
+    dump(doc.root);
+}
+
+fn dump(val: yaml.Value) void {
+    switch (val) {
+        .scalar => |str| std.debug.print("scalar: {s}\n", .{str}),
+        .list => |list| {
+            std.debug.print("list: \n", .{});
+            for (list) |item| dump(item);
+            std.debug.print("end list\n", .{});
+        },
+        .map => |map| {
+            std.debug.print("map: \n", .{});
+            var iter = map.iterator();
+            while (iter.next()) |entry| {
+                std.debug.print("key: {s}\n", .{entry.key_ptr.*});
+                dump(entry.value_ptr.*);
+            }
+            std.debug.print("end map\n", .{});
+        },
+    }
+}