diff --git a/Compactable.cabal b/Compactable.cabal
--- a/Compactable.cabal
+++ b/Compactable.cabal
@@ -2,7 +2,7 @@
 -- documentation, see http://haskell.org/cabal/users-guide/
 
 name:                Compactable
-version:             0.1.0.0
+version:             0.1.0.1
 synopsis:            A generalization for containers that can be stripped of Nothing
 description:         Sometimes you have a collection of Maybes,
                      and you want to extract the values. Actual that happens a whole lot.
diff --git a/src/Control/Compactable.hs b/src/Control/Compactable.hs
--- a/src/Control/Compactable.hs
+++ b/src/Control/Compactable.hs
@@ -200,7 +200,17 @@
 
 instance Compactable Vector
 
+instance Compactable (Const r) where
+    compact (Const r) = Const r
+    {-# INLINABLE compact #-}
 
+instance Monoid m => Compactable (Either m) where
+    compact (Right (Just x)) = Right x
+    compact (Right _)        = Left mempty
+    compact (Left x)         = Left x
+    {-# INLINABLE compact #-}
+
+
 fforMaybe :: (Compactable f, Functor f) => f a -> (a -> Maybe b) -> f b
 fforMaybe = flip fmapMaybe
 
@@ -218,11 +228,11 @@
 
 
 applyMaybeM :: (Compactable f, Monad f) => f (a -> MaybeT f b) -> f a -> f b
-applyMaybeM fa x = compact . join $ runMaybeT <$> (fa <*> x)
+applyMaybeM fa = compact . join . fmap runMaybeT . (fa <*>)
 
 
 bindMaybeM :: (Compactable f, Monad f) => f a -> (a -> f (MaybeT f b)) -> f b
-bindMaybeM x f = compact . join . fmap runMaybeT $ x >>= f
+bindMaybeM x = compact . join . fmap runMaybeT . (x >>=)
 
 
 traverseMaybeM :: (Monad m, Compactable t, Traversable t) => (a -> MaybeT m b) -> t a -> m (t b)