feat: use some Bevy systems to print some messages

src/main.rs

@@ -1,3 +1,30 @@
+use bevy::prelude::*;
+
 fn main() {
-    println!("Hello, world!");
+    App::new()
+        .add_startup_system(add_default_sprites)
+        .add_system(hello_world)
+        .add_system(print_sprite_names)
+        .run();
+}
+
+fn hello_world() {
+    println!("hello, world!");
+}
+
+#[derive(Component)]
+struct Sprite;
+
+#[derive(Component)]
+struct Name(String);
+
+fn add_default_sprites(mut commands: Commands) {
+    commands.spawn().insert(Sprite).insert(Name("Sprite 1".to_string()));
+    commands.spawn().insert(Sprite).insert(Name("Sprite 2".to_string()));
+}
+
+fn print_sprite_names(query: Query<&Name, With<Sprite>>) {
+    for name in query.iter() {
+        println!("found a sprite named {}", name.0);
+    }
 }