X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=Text%2FRead.hs;h=bcb2d0930ab395ab8f70bc0cfc99c723b5a906f9;hb=b0f8af46ab1a89f107f2d678d17b765cd97ff59f;hp=7d105fb8f054e10b7ac295dab24a7a8c7d43c62e;hpb=f7a485978f04e84b086f1974b88887cc72d832d0;p=ghc-base.git

diff --git a/Text/Read.hs b/Text/Read.hs
index 7d105fb..bcb2d09 100644
--- a/Text/Read.hs
+++ b/Text/Read.hs
@@ -1,4 +1,4 @@
-{-# OPTIONS -fno-implicit-prelude #-}
+{-# OPTIONS_GHC -fno-implicit-prelude #-}
 -----------------------------------------------------------------------------
 -- |
 -- Module      :  Text.Read
@@ -7,24 +7,64 @@
 -- 
 -- Maintainer  :  libraries@haskell.org
 -- Stability   :  provisional
--- Portability :  portable
+-- Portability :  non-portable (uses Text.ParserCombinators.ReadP)
 --
--- Exiting the program.
+-- Converting strings to values.
+--
+-- The "Text.Read" library is the canonical library to import for
+-- 'Read'-class facilities.  For GHC only, it offers an extended and much
+-- improved 'Read' class, which constitutes a proposed alternative to the 
+-- Haskell 98 'Read'.  In particular, writing parsers is easier, and
+-- the parsers are much more efficient.
 --
 -----------------------------------------------------------------------------
 
 module Text.Read (
+   -- * The 'Read' class
+   Read(..),		-- The Read class
    ReadS, 		-- String -> Maybe (a,String)
-   Read(
-      readsPrec,	-- :: Int -> ReadS a
-      readList		-- :: ReadS [a]
-    ),
+
+   -- * Haskell 98 functions
    reads,		-- :: (Read a) => ReadS a
    read,		-- :: (Read a) => String -> a
    readParen, 		-- :: Bool -> ReadS a -> ReadS a
    lex,			-- :: ReadS String
+
+#if defined(__GLASGOW_HASKELL__) || defined(__HUGS__)
+   -- * New parsing functions
+   module Text.ParserCombinators.ReadPrec,
+   L.Lexeme(..),	
+   lexP,		-- :: ReadPrec Lexeme
+   parens,		-- :: ReadPrec a -> ReadPrec a
+#endif
+#ifdef __GLASGOW_HASKELL__
+   readListDefault,	-- :: Read a => ReadS [a]
+   readListPrecDefault,	-- :: Read a => ReadPrec [a]
+#endif
+
  ) where
 
 #ifdef __GLASGOW_HASKELL__
 import GHC.Read
 #endif   
+#if defined(__GLASGOW_HASKELL__) || defined(__HUGS__)
+import Text.ParserCombinators.ReadPrec
+import qualified Text.Read.Lex as L
+#endif   
+
+#ifdef __HUGS__
+-- copied from GHC.Read
+
+lexP :: ReadPrec L.Lexeme
+lexP = lift L.lex
+
+parens :: ReadPrec a -> ReadPrec a
+parens p = optional
+ where
+  optional  = p +++ mandatory
+  mandatory = do
+    L.Punc "(" <- lexP
+    x          <- reset optional
+    L.Punc ")" <- lexP
+    return x
+#endif