2 files changed, 94 insertions, 3 deletions
diff --git a/ecs/examples/multiple_queries.rs b/ecs/examples/multiple_queries.rs
new file mode 100644
index 0000000..a4a5d2d
--- /dev/null
+++ b/ecs/examples/multiple_queries.rs
@@ -0,0 +1,87 @@
+use std::fmt::Display;
+
+use ecs::{Query, World};
+
+struct Health
+{
+    health: u32,
+}
+
+enum AttackStrength
+{
+    Strong,
+    Weak,
+}
+
+struct EnemyName
+{
+    name: String,
+}
+
+impl Display for EnemyName
+{
+    fn fmt(&self, formatter: &mut std::fmt::Formatter<'_>) -> std::fmt::Result
+    {
+        self.name.fmt(formatter)
+    }
+}
+
+fn say_hello(
+    mut query: Query<(AttackStrength,)>,
+    mut enemy_query: Query<(Health, EnemyName)>,
+)
+{
+    for (attack_strength,) in query.iter_mut() {
+        for (health, enemy_name) in enemy_query.iter_mut() {
+            let damage = match attack_strength {
+                AttackStrength::Strong => 20,
+                AttackStrength::Weak => 10,
+            };
+
+            if health.health <= damage {
+                println!("Enemy '{enemy_name}' died");
+
+                health.health = 0;
+
+                continue;
+            }
+
+            health.health -= damage;
+
+            println!("Enemy '{enemy_name}' took {damage} damage");
+        }
+    }
+}
+
+#[derive(Debug, PartialEq, Eq, Hash)]
+enum Event
+{
+    Start,
+}
+
+fn main()
+{
+    let mut world = World::<Event>::new();
+
+    world.register_system(Event::Start, say_hello);
+
+    world.create_entity((
+        Health { health: 100 },
+        EnemyName { name: "Big spider".to_string() },
+    ));
+
+    world.create_entity((
+        Health { health: 30 },
+        EnemyName { name: "Small goblin".to_string() },
+    ));
+
+    world.create_entity((
+        Health { health: 30 },
+        EnemyName { name: "Headcrab".to_string() },
+    ));
+
+    world.create_entity((AttackStrength::Strong,));
+    world.create_entity((AttackStrength::Weak,));
+
+    world.emit(&Event::Start);
+}
diff --git a/ecs/examples/with_local.rs b/ecs/examples/with_local.rs
index d7af0e0..0bd8f66 100644
--- a/ecs/examples/with_local.rs
+++ b/ecs/examples/with_local.rs
@@ -1,5 +1,5 @@
 use ecs::component::Local;
-use ecs::system::{Into, System};
+use ecs::system::{Input as SystemInput, Into, System};
 use ecs::{Query, World};
 
 struct SomeData
@@ -17,6 +17,8 @@ struct SayHelloState
     cnt: usize,
 }
 
+impl SystemInput for SayHelloState {}
+
 fn say_hello(mut query: Query<(SomeData, String)>, mut state: Local<SayHelloState>)
 {
     for (data, text) in query.iter_mut() {
@@ -50,14 +52,16 @@ fn main()
 
     world.register_system(
         Event::Update,
-        say_hello.into_system().initialize(SayHelloState { cnt: 0 }),
+        say_hello
+            .into_system()
+            .initialize((SayHelloState { cnt: 0 },)),
     );
 
     world.register_system(
         Event::Update,
         say_whats_up
             .into_system()
-            .initialize(SayHelloState { cnt: 0 }),
+            .initialize((SayHelloState { cnt: 0 },)),
     );
 
     world.create_entity((