1 files changed, 1 insertions, 3 deletions

diff --git a/ws2015/ffp/blaetter/07/FFP_U07_Monaden2.hs b/ws2015/ffp/blaetter/07/FFP_U07_Monaden2.hs
index 8e92dee..7939d36 100644
--- a/ws2015/ffp/blaetter/07/FFP_U07_Monaden2.hs
+++ b/ws2015/ffp/blaetter/07/FFP_U07_Monaden2.hs
@@ -282,13 +282,11 @@ memoWinchance atts defs = runST (newSTRef Map.empty >>= memoWinchance' atts defs
 memoWinchance' :: forall s. [Monster] -> [Monster] -> STRef s MM -> ST s Double
 memoWinchance' [] _ _ = return 0 -- We do this here so we don't clutter our manual with entries for empty lists
 memoWinchance' _ [] _ = return 1
-memoWinchance' atts defs mmRef = recall >>= fromMaybeM (winchance >>= memoize)
+memoWinchance' atts defs mmRef = recall >>= maybe (winchance >>= memoize) return
   where
     recall = Map.lookup (atts, defs) <$> readSTRef mmRef
     memoize x = modifySTRef mmRef (Map.insert (atts, defs) x) >> return x
     winchance = winchance' atts defs mmRef
-    fromMaybeM x Nothing = x
-    fromMaybeM _ (Just x) = return x
 
     winchance' :: forall s. [Monster] -> [Monster] -> STRef s MM -> ST s Double
     winchance' allatts@(a:atts) alldefs@(d:defs) mmRef