+groupWith f xs = build (\c n -> groupByFB c n (\x y -> f x == f y) (sortWith f xs))
+
+groupByFB :: ([a] -> lst -> lst) -> lst -> (a -> a -> Bool) -> [a] -> lst
+groupByFB c n eq xs0 = groupByFBCore xs0
+ where groupByFBCore [] = n
+ groupByFBCore (x:xs) = c (x:ys) (groupByFBCore zs)
+ where (ys, zs) = span (eq x) xs
+
+
+-- -----------------------------------------------------------------------------
+-- tracing
+
+traceEvent :: String -> IO ()
+traceEvent msg = do
+ withCString msg $ \(Ptr p) -> IO $ \s ->
+ case traceEvent# p s of s' -> (# s', () #)
+
+
+
+{- **********************************************************************
+* *
+* SpecConstr annotation *
+* *
+********************************************************************** -}
+
+-- Annotating a type with NoSpecConstr will make SpecConstr
+-- not specialise for arguments of that type.
+
+-- This data type is defined here, rather than in the SpecConstr module
+-- itself, so that importing it doesn't force stupidly linking the
+-- entire ghc package at runtime
+
+data SpecConstrAnnotation = NoSpecConstr | ForceSpecConstr
+ deriving( Data, Typeable, Eq )
+