Continue to refactor zoning to be more stream-based

src/Dodge/Update.hs

@@ -366,14 +366,14 @@ crSpring c w = IM.foldl' (flip $ crCrSpring c) w cs
     cs = creaturesNearPoint (_crPos c) w
 
 crCrSpring :: Creature -> Creature -> World -> World
-crCrSpring c1 c2 w 
-    | id1 == id2 = w
-    | vec == V2 0 0 = w
-    | diff >= comRad = w
-    | otherwise = over creatures
+crCrSpring c1 c2
+    | id1 == id2    = id
+    | vec == V2 0 0 = id
+    | diff >= comRad = id
+    | otherwise = creatures %~
         ( over (ix id1 . crPos) (+.+ overlap1)
         . over (ix id2 . crPos) (-.- overlap2)
-        ) w
+        )
   where 
     id1  = _crID c1
     id2  = _crID c2