X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=Data%2FTraversable.hs;h=3d3ae70eff395b5e8d55f3785457434c791d2aa5;hb=b22112520b01c4906eebd0b6894d4bf2665c11e2;hp=969e720612591426a791baf6cc10ab7c6b511a3e;hpb=c7dc14cd5106c9e3c5d481a09b6e6241f662e99d;p=ghc-base.git

diff --git a/Data/Traversable.hs b/Data/Traversable.hs
index 969e720..3d3ae70 100644
--- a/Data/Traversable.hs
+++ b/Data/Traversable.hs
@@ -62,7 +62,7 @@ import Array
 --
 -- a suitable instance would be
 --
--- > instance Traversable Tree
+-- > instance Traversable Tree where
 -- >    traverse f Empty = pure Empty
 -- >    traverse f (Leaf x) = Leaf <$> f x
 -- >    traverse f (Node l k r) = Node <$> traverse f l <*> f k <*> traverse f r
@@ -103,10 +103,11 @@ class (Functor t, Foldable t) => Traversable t where
 -- instances for Prelude types
 
 instance Traversable Maybe where
-        traverse f Nothing = pure Nothing
+        traverse _ Nothing = pure Nothing
         traverse f (Just x) = Just <$> f x
 
 instance Traversable [] where
+        {-# INLINE traverse #-} -- so that traverse can fuse
         traverse f = Prelude.foldr cons_f (pure [])
           where cons_f x ys = (:) <$> f x <*> ys
 
@@ -171,6 +172,7 @@ mapAccumR f s t = runStateR (traverse (StateR . flip f) t) s
 
 -- | This function may be used as a value for `fmap` in a `Functor` instance.
 fmapDefault :: Traversable t => (a -> b) -> t a -> t b
+{-# INLINE fmapDefault #-}
 fmapDefault f = getId . traverse (Id . f)
 
 -- | This function may be used as a value for `Data.Foldable.foldMap`