Fix CodingStyle#Warnings URLs

[ghc-hetmet.git] / compiler / utils / Util.lhs

diff --git a/compiler/utils/Util.lhs b/compiler/utils/Util.lhs
index 8473faf..2d5e740 100644 (file)
--- a/compiler/utils/Util.lhs
+++ b/compiler/utils/Util.lhs
@@ -5,6 +5,13 @@
 \section[Util]{Highly random utility functions}
 
 \begin{code}
+{-# OPTIONS -w #-}
+-- The above warning supression flag is a temporary kludge.
+-- While working on this module you are encouraged to remove it and fix
+-- any warnings in the module. See
+--     http://hackage.haskell.org/trac/ghc/wiki/Commentary/CodingStyle#Warnings
+-- for details
+
 module Util (
 
        -- general list processing
@@ -26,7 +33,7 @@ module Util (
        nTimes,
 
        -- sorting
-       sortLe, sortWith,
+       sortLe, sortWith, on,
 
        -- transitive closures
        transitiveClosure,
@@ -79,9 +86,12 @@ 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 +99,11 @@ 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 +464,10 @@ 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 +601,8 @@ 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