Add laser central room, using new placement/roompos functionality

src/Dodge/Placement/PlaceSpot.hs

@@ -34,7 +34,7 @@ import Data.Bifunctor
 placeSpot :: (World,Room) -> Placement -> ( (World,Room), [Placement] )
 placeSpot (w,rm) plmnt = case plmnt of
     Placement{_plSpot = PSRoomRand i} -> placeSpotRoomRand rm i plmnt w
-    Placement{_plSpot = PSLnk extract eff fallback} -> placeSpotUsingLink w rm plmnt extract eff fallback
+    Placement{_plSpot = PSPos extract eff fallback} -> placeSpotUsingLink w rm plmnt extract eff fallback
     Placement{} ->
         let (i,w') = placeSpotID (shiftPSBy shift (_plSpot plmnt)) (_plType plmnt) w
             newplmnt = plmnt & plMID ?~ i
@@ -52,12 +52,12 @@ placeSpot (w,rm) plmnt = case plmnt of
 
 -- this should be tidied up
 placeSpotUsingLink :: World -> Room -> Placement 
-    -> (RoomPos -> Maybe PlacementSpot)
+    -> (RoomPos -> Maybe (PlacementSpot,RoomPos))
     -> (RoomPos -> Room -> Room)
     -> Maybe Placement
     -> ((World, Room), [Placement])
 placeSpotUsingLink w rm plmnt extract eff fallback = case searchedPoss (_rmPos rm) of
-    Just (ps,pos,newrmpos) -> placeSpot (w, eff pos $ rm & rmPos .~ newrmpos) (plmnt & plSpot .~ ps)
+    Just (ps,rmposs) -> placeSpot (w, eff (head rmposs) $ rm & rmPos .~ rmposs) (plmnt & plSpot .~ ps)
     Nothing -> case fallback of
         Nothing -> ((w,rm),[plmnt])
         Just plmnt' -> placeSpot (w,rm) plmnt'
@@ -65,7 +65,7 @@ placeSpotUsingLink w rm plmnt extract eff fallback = case searchedPoss (_rmPos r
     searchedPoss [] = error "no correct pos type for lnk placement"
     searchedPoss (pos:poss) = case extract pos of
         Nothing -> second (pos:) <$> searchedPoss poss
-        Just ps -> Just ( ps,pos, poss)
+        Just (ps,rmpos) -> Just ( ps,rmpos:poss)
 
 placeSpotRoomRand :: Room -> Int -> Placement -> World -> ((World,Room),[Placement])
 placeSpotRoomRand rm i plmnt w =