Make _targetCr an Int id rather than a full creature

src/Dodge/Creature/Impulse.hs

@@ -2,6 +2,7 @@
 
 module Dodge.Creature.Impulse (impulsiveAIBefore) where
 
+import Data.Maybe
 import Linear
 import NewInt
 import Dodge.Creature.MoveType
@@ -64,12 +65,14 @@ followImpulse cr w imp = case imp of
     ArbitraryImpulseFunction f -> crup $ doWdCrCr f w cr
     ArbitraryImpulse f -> followImpulse cr w (doCrWdImp f cr w)
     ArbitraryImpulseEffect f -> (doCrWdWd f cr, cr)
-    ImpulseUseTargetCID f -> case cr ^? crIntention . targetCr . _Just of
-        Just tcr -> followImpulse cr w (doIntImp f $ _crID tcr)
-        _ -> crup cr
-    ImpulseUseTarget f -> case cr ^? crIntention . targetCr . _Just of
-        Just tcr -> followImpulse cr w (doCrImp f tcr)
-        _ -> crup cr
+    ImpulseUseTargetCID f -> fromMaybe (crup cr) $ do
+        i <- cr ^? crIntention . targetCr . _Just
+        tcr <- w ^? cWorld . lWorld . creatures . ix i
+        return $ followImpulse cr w (doIntImp f $ _crID tcr)
+    ImpulseUseTarget f -> fromMaybe (crup cr) $ do
+        i <- cr ^? crIntention . targetCr . _Just
+        tcr <- w ^? cWorld . lWorld . creatures . ix i
+        return $ followImpulse cr w (doCrImp f tcr)
     ImpulseUseAheadPos f -> followImpulse cr w (doP2Imp f (cr ^. crPos . _xy +.+ 20 *.* unitVectorAtAngle (_crDir cr)))
     MvForward -> crup $ crMvForward speed (w ^. cWorld . lWorld) cr
     MvTurnToward p ->