Add neighbours function to position

src/system/mod.rs

@@ -3,6 +3,7 @@ use std::ops::Add;
 pub mod walker;
 pub mod storage;
 pub mod model;
+pub mod generic;
 
 pub(crate) const DIM: u32 = 2;
 
@@ -17,6 +18,15 @@ impl Position {
     pub fn in_direction(direction: u32, value: i32) -> Self {
         if direction == 0 { Position(value, 0) } else { Position(0, value) }
     }
+
+    pub fn neighbours(&self) -> impl Iterator<Item=Self> + '_ {
+        let a = (0..DIM).into_iter();
+
+        return a.flat_map(|direction| [
+            self.clone() + Position::in_direction(direction, 1),
+            self.clone() + Position::in_direction(direction, -1),
+        ]);
+    }
 }
 
 impl Add for Position {

src/system/model.rs

@@ -87,16 +87,11 @@ impl<R: Rng, S: Storage, W: Walker<R>> DLASystem<R, S, W> {
     }
 
     fn check_stick(&mut self, position: &Position) -> bool {
-        for direction in 0..DIM {
-            for sign in [-1, 1] {
-                let neighbour = position.clone() + Position::in_direction(direction, sign);
-                if self.storage.at(&neighbour) && self.rng.gen_range(0.0f32..=1.0) < self.stick_probability {
-                    return true;
-                }
-            }
-        }
-
-        return false;
+        position.neighbours()
+            .any(|neighbour|
+                self.storage.at(&neighbour)
+                    && self.rng.gen_range(0.0f32..=1.0) < self.stick_probability
+            )
     }
 
     fn spawn_particle(&mut self) {