1 files changed, 4 insertions, 8 deletions

diff --git a/events/src/Events/Types/NDT.hs b/events/src/Events/Types/NDT.hs
index 848ad39..a417029 100644
--- a/events/src/Events/Types/NDT.hs
+++ b/events/src/Events/Types/NDT.hs
@@ -1,6 +1,5 @@
 {-# LANGUAGE GADTs #-}
 {-# LANGUAGE TupleSections #-}
-{-# LANGUAGE ViewPatterns #-}
 {-# LANGUAGE FlexibleContexts, FlexibleInstances #-}
 {-# LANGUAGE MultiParamTypeClasses, UndecidableInstances #-}
 
@@ -15,6 +14,7 @@ import Data.Monoid
 import Data.Foldable (foldr)
 import Data.Maybe
 import Data.Either
+import Data.Bool (bool)
 
 import Control.Applicative (Alternative)
 import qualified Control.Applicative as Alt (Alternative(..))
@@ -41,7 +41,7 @@ instance Functor m => Functor (NDT m) where
 
 instance Applicative m => Applicative (NDT m) where
   pure x = NDTCons . pure $ Just (x, empty)
-  fs <*> xs = fs >>= (\f -> xs >>= pure . (f $))
+  fs <*> xs = fs >>= (\f -> xs >>= pure . f)
 
 instance Applicative m => Monad (NDT m) where
   return = pure
@@ -55,7 +55,7 @@ instance Monad m => Monoid (NDT m a) where
   mappend x y@(NDTBind _ _) = NDTBind x return <> y
 
 instance MonadTrans NDT where
-  lift = NDTCons . fmap Just . fmap (,empty)
+  lift = NDTCons . fmap (Just . (, empty))
 
 instance Monad m => Alternative (NDT m) where
   empty = mempty
@@ -88,11 +88,7 @@ foldNDT sel (NDTCons mx) = do
   mx' <- mx
   case mx' of
     Nothing -> return mempty
-    Just (x, mxs) -> do
-      continue <- sel x
-      case continue of
-        False -> return mempty
-        True  -> (pure x <>) <$> foldNDT sel mxs
+    Just (x, mxs) -> bool (return mempty) ((pure x <>) <$> foldNDT sel mxs) =<< sel x
 foldNDT sel (NDTBind (NDTCons x) f) = do
   x' <- x
   case x' of