X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=Data%2FOrd.hs;h=fd291ae960e8ddfe6899c934c83fb2e828535574;hb=HEAD;hp=2be636c213af963a494f8e6e3cfab534f90a2693;hpb=41f0208eabdb92852b6e463406aca68d32e08d8c;p=ghc-base.git

diff --git a/Data/Ord.hs b/Data/Ord.hs
index 2be636c..fd291ae 100644
--- a/Data/Ord.hs
+++ b/Data/Ord.hs
@@ -1,4 +1,5 @@
-{-# OPTIONS_GHC -fno-implicit-prelude #-}
+{-# LANGUAGE CPP, NoImplicitPrelude #-}
+
 -----------------------------------------------------------------------------
 -- |
 -- Module      :  Data.Ord
@@ -15,7 +16,7 @@
 
 module Data.Ord (
    Ord(..),
-   Ordering,
+   Ordering(..),
    comparing,
  ) where
 
@@ -23,5 +24,12 @@ module Data.Ord (
 import GHC.Base
 #endif
 
+-- | 
+-- > comparing p x y = compare (p x) (p y)
+--
+-- Useful combinator for use in conjunction with the @xxxBy@ family
+-- of functions from "Data.List", for example:
+--
+-- >   ... sortBy (comparing fst) ...
 comparing :: (Ord a) => (b -> a) -> b -> b -> Ordering
 comparing p x y = compare (p x) (p y)