Simplify block/wall destruction

This uses a right fold, so might be slower than a strict left fold

src/Dodge/Wall/Damage.hs

@@ -2,7 +2,8 @@
 {- | Controls a walls response to external damage.
  - Indestructible walls may still produce sparks, dust etc
 -}
-module Dodge.Wall.Damage (damageWall) where
+module Dodge.Wall.Damage (damageWall
+    ) where
 
 import Linear
 import Data.Maybe
@@ -22,19 +23,32 @@ import Dodge.Data.World
 import LensHelp
 import qualified Data.Set as S
 
--- maybeDestroyDoor should rather happen during the door mechanism update
-damageWall :: Damage -> Wall -> (S.Set Int2,World) -> (S.Set Int2,World)
-damageWall dt wl (is,w) = case _wlStructure wl of
-    MachinePart mcid -> (,) is $ w' & cWorld . lWorld . machines . ix mcid . mcDamage .:~ dt
+---- maybeDestroyDoor should rather happen during the door mechanism update
+--damageWall :: Damage -> Wall -> (S.Set Int2,World) -> (S.Set Int2,World)
+--damageWall dt wl (is,w) = case _wlStructure wl of
+--    MachinePart mcid -> (,) is $ w' & cWorld . lWorld . machines . ix mcid . mcDamage .:~ dt
+--    BlockPart blid ->
+--        w' & cWorld . lWorld . blocks . ix blid . blHP -~ dmam
+--            & maybeDestroyBlock blid
+--            & _1 <>~ is
+--    DoorPart drid _ ->
+--        w' & cWorld . lWorld . doors . ix drid . drHP -~ dmam
+--            & maybeDestroyDoor drid
+--            & _1 <>~ is
+--    _ -> (is, w')
+--  where
+--    (dmam,w') = damMatSideEffect dt (_wlMaterial wl) (Right wl) w
+
+damageWall ::  Wall -> Damage ->World -> (S.Set Int2,World)
+damageWall wl dt w = case _wlStructure wl of
+    MachinePart mcid -> (,) mempty $ w' & cWorld . lWorld . machines . ix mcid . mcDamage .:~ dt
     BlockPart blid ->
         w' & cWorld . lWorld . blocks . ix blid . blHP -~ dmam
             & maybeDestroyBlock blid
-            & _1 <>~ is
     DoorPart drid _ ->
         w' & cWorld . lWorld . doors . ix drid . drHP -~ dmam
             & maybeDestroyDoor drid
-            & _1 <>~ is
-    _ -> (is, w')
+    _ -> (mempty, w')
   where
     (dmam,w') = damMatSideEffect dt (_wlMaterial wl) (Right wl) w