Use explicit language extensions & remove extension fields from base.cabal

[ghc-base.git] / Text / Show / Functions.hs

diff --git a/Text/Show/Functions.hs b/Text/Show/Functions.hs
index b246c44..1ae46aa 100644 (file)
--- a/Text/Show/Functions.hs
+++ b/Text/Show/Functions.hs
@@ -1,22 +1,37 @@
+{-# LANGUAGE CPP #-}
+-- This module deliberately declares orphan instances:
+{-# OPTIONS_GHC -fno-warn-orphans #-}
+
 -----------------------------------------------------------------------------
--- 
+-- |
 -- Module      :  Text.Show.Functions
 -- Copyright   :  (c) The University of Glasgow 2001
--- License     :  BSD-style (see the file libraries/core/LICENSE)
+-- License     :  BSD-style (see the file libraries/base/LICENSE)
 -- 
 -- Maintainer  :  libraries@haskell.org
 -- Stability   :  provisional
 -- Portability :  portable
 --
--- $Id: Functions.hs,v 1.1 2001/06/28 14:15:04 simonmar Exp $
+-- Optional instance of 'Text.Show.Show' for functions:
 --
--- Optional instance of Text.Show.Show for functions.
+-- > instance Show (a -> b) where
+-- >   showsPrec _ _ = showString \"\<function\>\"
 --
 -----------------------------------------------------------------------------
 
-module Text.Show.Functions where
+module Text.Show.Functions () where
 
 import Prelude
 
+#ifndef __NHC__
 instance Show (a -> b) where
        showsPrec _ _ = showString "<function>"
+#else
+instance (Show a,Show b) => Show (a->b) where
+  showsPrec d a = showString "<<function>>"
+
+  showsType a = showChar '(' . showsType value  . showString " -> " .
+                               showsType result . showChar ')'
+                where (value,result) = getTypes undefined
+                      getTypes x = (x,a x)
+#endif