Start work on lasguns

src/Dodge/WorldEvent/ThingsHit.hs

@@ -5,6 +5,7 @@ Find which objects lie upon a line.
 module Dodge.WorldEvent.ThingsHit
     ( thingsHit
     , thingHit
+    , thingHitFilt
     , thingsHitExceptCr
     )
     where
@@ -35,6 +36,13 @@ crsHit sp ep
         . overlap1SegCrs sp ep
         . crsNearSeg sp ep
 
+thingHitFilt :: (Creature -> Bool) -> (Wall -> Bool) 
+    -> Point2 -> Point2 -> World -> Maybe (Point2, Either Creature Wall)
+thingHitFilt fcr fwl sp ep = runIdentity . S.head_ . S.filter (f . snd) . thingsHit sp ep
+  where
+    f (Left cr) = fcr cr
+    f (Right wl) = fwl wl
+
 thingHit :: Point2 -> Point2 -> World -> Maybe (Point2, Either Creature Wall)
 thingHit sp ep = runIdentity . S.head_ . thingsHit sp ep