X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=Data%2FTraversable.hs;h=df10679cf40e27cc8252e16fa5766340b770bd7d;hb=8d585f7c5ad8c4b46f9ca58931e1379abbd359af;hp=7ad399150127d92d96d7ce91d629afbd1214d269;hpb=38b2f3cef719c9aab2223dcb417958f5d247c212;p=ghc-base.git

diff --git a/Data/Traversable.hs b/Data/Traversable.hs
index 7ad3991..df10679 100644
--- a/Data/Traversable.hs
+++ b/Data/Traversable.hs
@@ -43,6 +43,12 @@ import Control.Applicative
 import Data.Foldable (Foldable())
 import Data.Monoid (Monoid)
 
+#if defined(__GLASGOW_HASKELL__)
+import GHC.Arr
+#elif defined(__HUGS__)
+import Hugs.Array
+#endif
+
 -- | Functors representing data structures that can be traversed from
 -- left to right.
 --
@@ -104,6 +110,11 @@ instance Traversable [] where
 
         mapM = Prelude.mapM
 
+#ifndef __NHC__
+instance Ix i => Traversable (Array i) where
+    traverse f arr = listArray (bounds arr) `fmap` traverse f (elems arr)
+#endif
+
 -- general functions
 
 -- | 'for' is 'traverse' with its arguments flipped.