diff --git a/lyra-ecs/src/lib.rs b/lyra-ecs/src/lib.rs
index f1c21fc..008adcb 100644
--- a/lyra-ecs/src/lib.rs
+++ b/lyra-ecs/src/lib.rs
@@ -29,6 +29,7 @@ mod tests;
 
 #[derive(Clone, Copy, Hash, PartialEq, Eq, PartialOrd, Ord)]
 pub enum Access {
+    None,
     Read,
     Write,
 }
\ No newline at end of file
diff --git a/lyra-ecs/src/system/mod.rs b/lyra-ecs/src/system/mod.rs
index c636a53..9b6d035 100644
--- a/lyra-ecs/src/system/mod.rs
+++ b/lyra-ecs/src/system/mod.rs
@@ -17,29 +17,33 @@ pub trait IntoSystem<T> {
     fn into_system(self) -> Self::System;
 }
 
-trait FnArg {
-    type Arg<'a>;
+pub trait FnArgFetcher {
+    type Arg<'a>: FnArg<Fetcher = Self>;
 
     fn new() -> Self;
 
-    unsafe fn get<'a>(&mut self, world: &'a World) -> Self::Arg<'a>;
+    /// Return the appropriate world access if this fetcher gets the world directly.
+    /// Return [`Access::None`] if you're only fetching components, or resources.
+    fn world_access(&self) -> Access {
+        Access::None
+    }
+
+    /// Get the arg from the world
+    unsafe fn get<'a>(&mut self, world: NonNull<World>) -> Self::Arg<'a>;
+}
+
+pub trait FnArg {
+    type Fetcher: FnArgFetcher;
 }
 
 pub struct FnSystem<F, Args> {
-    inner: F,//for<'a> fn(Args) -> anyhow::Result<()>
-    //args: Args,
-    _p: PhantomData<Args>,
+    inner: F,
+    args: Args,
 }
 
-/* impl<'a, F, Q> System for FnSystem<F, Q>
-where
-    Q: FnArg,
-    F: Fn(Q::Arg<'a>,) -> anyhow::Result<()>, */
-
-
 impl<F, A> System for FnSystem<F, A>
 where
-    A: FnArg,
+    A: FnArgFetcher,
     F: for<'a> FnMut(A::Arg<'a>) -> anyhow::Result<()>,
 {
     fn world_access(&self) -> Access {
@@ -47,8 +51,6 @@ where
     }
 
     fn execute(&mut self, world: NonNull<World>) -> anyhow::Result<()> {
-        let world = unsafe { world.as_ref() };
-        
         let mut a = A::new();
 
         let a = unsafe { a.get(world) };
@@ -59,65 +61,42 @@ where
     }
 }
 
-/* impl<F, A> IntoSystem<A> for F
+impl<F, A> IntoSystem<A> for F
 where
     A: FnArg,
-    F: for<'a> Fn(A::Arg<'a>) -> anyhow::Result<()>,
+    F: FnMut(A) -> anyhow::Result<()>,
+    F: for<'a> FnMut(<A::Fetcher as FnArgFetcher>::Arg<'a>) -> anyhow::Result<()>,
 {
-    type System = FnSystem<F, A>;
+    type System = FnSystem<F, A::Fetcher>;
 
     fn into_system(self) -> Self::System {
         FnSystem {
-            _p: PhantomData,
-            inner: self
-        }
-    }
-} */
-
-/* impl<F, Q> IntoSystem<Q> for F
-where
-    Q: Query,
-    F: for<'a> Fn(<FnArgStorage<Q> as FnArg>::Arg<'a>) -> anyhow::Result<()>,
-{
-    type System = FnSystem<F, FnArgStorage<Q>>;
-
-    fn into_system(self) -> Self::System {
-        FnSystem {
-            _p: PhantomData,
-            inner: self
-        }
-    }
-} */
-
-impl<F, Q> IntoSystem<Q> for F
-where
-    Q: Query,
-    F: for<'a> FnMut(<FnArgStorage<Q> as FnArg>::Arg<'a>) -> anyhow::Result<()>,
-{
-    type System = FnSystem<F, FnArgStorage<Q>>;
-
-    fn into_system(self) -> Self::System {
-        FnSystem {
-            _p: PhantomData,
+            args: A::Fetcher::new(),
             inner: self
         }
     }
 }
 
-pub struct FnArgStorage<Q: Query> {
-    query: Q,
+/// An ArgFetcher implementation for query [`View`]s
+pub struct ViewArgFetcher<Q> {
+    query: Q
 }
 
-impl<Q: Query> FnArg for FnArgStorage<Q> {
-    type Arg<'b> = View<'b, Q>;
+impl<'a, Q: Query> FnArg for View<'a, Q> {
+    type Fetcher = ViewArgFetcher<Q>;
+}
+
+impl<Q: Query> FnArgFetcher for ViewArgFetcher<Q> {
+    type Arg<'a> = View<'a, Q>;
 
     fn new() -> Self {
-        FnArgStorage {
+        ViewArgFetcher {
             query: Q::new(),
         }
     }
 
-    unsafe fn get<'b>(&mut self, world: &'b World) -> Self::Arg<'b> {
+    unsafe fn get<'a>(&mut self, world: NonNull<World>) -> Self::Arg<'a> {
+        let world = &*world.as_ptr();
         let arch = world.archetypes.values().collect();
         let v = View::new(world, self.query, arch);
 
@@ -125,25 +104,80 @@ impl<Q: Query> FnArg for FnArgStorage<Q> {
     }
 }
 
+/// An ArgFetcher implementation for borrowing the [`World`].
+pub struct WorldArgFetcher;
+
+impl<'a> FnArg for &'a World {
+    type Fetcher = WorldArgFetcher;
+}
+
+impl FnArgFetcher for WorldArgFetcher {
+    type Arg<'a> = &'a World;
+
+    fn new() -> Self {
+        WorldArgFetcher
+    }
+
+    fn world_access(&self) -> Access {
+        Access::Read
+    }
+
+    unsafe fn get<'a>(&mut self, world: NonNull<World>) -> Self::Arg<'a> {
+        &*world.as_ptr()
+    }
+
+}
+
+/// An ArgFetcher implementation for mutably borrowing the [`World`].
+pub struct WorldMutArgFetcher;
+
+impl<'a> FnArg for &'a mut World {
+    type Fetcher = WorldMutArgFetcher;
+}
+
+impl FnArgFetcher for WorldMutArgFetcher {
+    type Arg<'a> = &'a mut World;
+
+    fn new() -> Self {
+        WorldMutArgFetcher
+    }
+
+    fn world_access(&self) -> Access {
+        Access::Write
+    }
+
+    unsafe fn get<'a>(&mut self, world: NonNull<World>) -> Self::Arg<'a> {
+        &mut *world.as_ptr()
+    }
+}
+
 #[cfg(test)]
 mod tests {
-    use std::{ptr::NonNull, sync::atomic::{AtomicU8, Ordering}, rc::Rc, ops::Add};
+    use std::ptr::NonNull;
 
     use crate::{tests::{Vec2, Vec3}, View, QueryBorrow, world::World};
     use super::{System, IntoSystem};
 
+    struct SomeCounter(u32);
+
     #[test]
     fn simple_system() {
         let mut world = World::new();
-        world.spawn((Vec2::rand(),));
-        world.spawn((Vec2::rand(),));
-        world.spawn((Vec2::rand(),));
-        world.spawn((Vec2::rand(),));
+        let vecs = &[Vec2::rand(), Vec2::rand(), Vec2::rand(), Vec2::rand()];
+        world.spawn((vecs[0],));
+        world.spawn((vecs[1],));
+        world.spawn((vecs[2],));
+        world.spawn((vecs[3],));
 
         let mut count = 0;
 
         let test_system = |view: View<QueryBorrow<Vec2>>| -> anyhow::Result<()> {
+            let mut vecs = vecs.to_vec();
             for v in view.into_iter() {
+                let pos = vecs.iter().position(|vec| *vec == *v)
+                    .expect("Failure to find vec inside list");
+                vecs.remove(pos);
+
                 println!("Got v at: {:?}", v);
                 count += 1;
             }
@@ -179,4 +213,24 @@ mod tests {
 
         assert_eq!(count, 2);
     }
+
+    #[test]
+    fn world_system() {
+        let mut world = World::new();
+        world.spawn((Vec2::rand(), Vec3::rand()));
+        world.spawn((Vec2::rand(), Vec3::rand()));
+        world.add_resource(SomeCounter(0));
+
+        let test_system = |world: &World| -> anyhow::Result<()> {
+            let mut counter = world.get_resource_mut::<SomeCounter>();
+            counter.0 += 10;
+
+            Ok(())
+        };
+
+        test_system.into_system().execute(NonNull::from(&world)).unwrap();
+
+        let counter = world.get_resource::<SomeCounter>();
+        assert_eq!(counter.0, 10);
+    }
 }
\ No newline at end of file