X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=compiler%2Futils%2FUtil.lhs;h=e5f702355244f20521c63c1ddbb27f84aba924d6;hb=f0d0e9d63ee27a12e80b6f069be5e9d4b55ca545;hp=8473faf42eeb94d29641c35e850b2e5d7a9454d7;hpb=8100c58a929d993d2dd7022412ed6113cf97fba7;p=ghc-hetmet.git

diff --git a/compiler/utils/Util.lhs b/compiler/utils/Util.lhs
index 8473faf..e5f7023 100644
--- a/compiler/utils/Util.lhs
+++ b/compiler/utils/Util.lhs
@@ -26,7 +26,7 @@ module Util (
 	nTimes,
 
 	-- sorting
-	sortLe, sortWith,
+	sortLe, sortWith, on,
 
 	-- transitive closures
 	transitiveClosure,
@@ -79,9 +79,12 @@ module Util (
 
 #include "HsVersions.h"
 
-import Panic		( panic, trace )
 import FastTypes
 
+#ifdef DEBUG
+import Panic		( panic, trace )
+#endif
+
 import Control.Exception ( Exception(..), finally, catchDyn, throw )
 import qualified Control.Exception as Exception
 import Data.Dynamic	( Typeable )
@@ -89,10 +92,11 @@ import Data.IORef	( IORef, newIORef )
 import System.IO.Unsafe	( unsafePerformIO )
 import Data.IORef	( readIORef, writeIORef )
 
-import qualified Data.List as List ( elem, notElem )
-
+import qualified Data.List as List ( elem )
 #ifndef DEBUG
 import Data.List		( zipWith4 )
+#else
+import qualified Data.List as List ( notElem )
 #endif
 
 import Control.Monad	( when )
@@ -453,6 +457,10 @@ sortWith :: Ord b => (a->b) -> [a] -> [a]
 sortWith get_key xs = sortLe le xs
   where
     x `le` y = get_key x < get_key y	
+
+on :: (a -> a -> Ordering) -> (b -> a) -> b -> b -> Ordering
+on cmp sel = \x y -> sel x `cmp` sel y
+
 \end{code}
 
 %************************************************************************
@@ -586,6 +594,8 @@ cmpList cmp (a:as) (b:bs)
 \end{code}
 
 \begin{code}
+-- This (with a more general type) is Data.List.stripPrefix from GHC 6.8.
+-- This definition can be removed once we require at least 6.8 to build.
 maybePrefixMatch :: String -> String -> Maybe String
 maybePrefixMatch []    rest = Just rest
 maybePrefixMatch (_:_) []   = Nothing