Followed getting-started guide

src/main.rs

@@ -0,0 +1,54 @@
+
+use bevy::prelude::*;
+
+fn main() {
+    App::new()
+        .add_plugins((DefaultPlugins, HelloPlugin))
+        .run();
+}
+
+#[derive(Component)]
+struct Person;
+
+#[derive(Component)]
+struct Name(String);
+
+fn add_people(mut commands: Commands) {
+    commands.spawn((Person, Name("John".to_string())));
+    commands.spawn((Person, Name("Jack".to_string())));
+    commands.spawn((Person, Name("Bill".to_string())));
+}
+
+#[derive(Resource)]
+struct GreetTimer(Timer);
+
+fn greet_people(
+    time: Res<Time>,
+    mut timer: ResMut<GreetTimer>,
+    query: Query<&Name, With<Person>>
+) {
+    if timer.0.tick(time.delta()).just_finished() {
+        for name in &query {
+            println!("Hello {}!", name.0);
+        }
+    }
+}
+
+fn update_people(mut query: Query<&mut Name, With<Person>>) {
+    for mut name in &mut query {
+        if name.0 == "Bill" {
+            name.0 = "Jill".to_string();
+            break;
+        }
+    }
+}
+
+pub struct HelloPlugin;
+
+impl Plugin for HelloPlugin {
+    fn build(&self, app: &mut App){
+        app.insert_resource(GreetTimer(Timer::from_seconds(2.0, TimerMode::Repeating)))
+            .add_systems(Startup, add_people)
+            .add_systems(Update, (update_people, greet_people).chain());
+    }
+}