X-Git-Url: http://git.megacz.com/?p=ghc-base.git;a=blobdiff_plain;f=Prelude.hs;h=4c183ae38c9ad44a22a25c4bba5fa9149066cb62;hp=9de927d4275699fccb1bdad847fb2772b8848fa6;hb=HEAD;hpb=06bb288c8d7e2f46276f25c3ef16d091de8f3ded

diff --git a/Prelude.hs b/Prelude.hs
index 9de927d..4c183ae 100644
--- a/Prelude.hs
+++ b/Prelude.hs
@@ -1,4 +1,5 @@
-{-# OPTIONS -fno-implicit-prelude #-}
+{-# LANGUAGE CPP, NoImplicitPrelude, BangPatterns #-}
+
 -----------------------------------------------------------------------------
 -- |
 -- Module      :  Prelude
@@ -36,16 +37,16 @@ module Prelude (
     fst, snd, curry, uncurry,
 
 #if defined(__NHC__)
-    []((:), []),	-- Not legal Haskell 98;
-			-- ... available through built-in syntax
-    module Data.Tuple,	-- Includes tuple types
-    ()(..),		-- Not legal Haskell 98
-    (->),		-- ... available through built-in syntax
+    []((:), []),        -- Not legal Haskell 98;
+                        -- ... available through built-in syntax
+    module Data.Tuple,  -- Includes tuple types
+    ()(..),             -- Not legal Haskell 98
+    (->),               -- ... available through built-in syntax
 #endif
 #ifdef __HUGS__
-    (:),		-- Not legal Haskell 98
+    (:),                -- Not legal Haskell 98
 #endif
-    
+
     -- ** Basic type classes
     Eq((==), (/=)),
     Ord(compare, (<), (<=), (>=), (>), max, min),
@@ -72,7 +73,7 @@ module Prelude (
               isInfinite, isDenormalized, isIEEE, isNegativeZero, atan2),
 
     -- *** Numeric functions
-    subtract, even, odd, gcd, lcm, (^), (^^), 
+    subtract, even, odd, gcd, lcm, (^), (^^),
     fromIntegral, realToFrac,
 
     -- ** Monads and functors
@@ -87,7 +88,7 @@ module Prelude (
 
     -- * List operations
     map, (++), filter,
-    head, last, tail, init, null, length, (!!), 
+    head, last, tail, init, null, length, (!!),
     reverse,
     -- ** Reducing lists (folds)
     foldl, foldl1, foldr, foldr1,
@@ -119,8 +120,8 @@ module Prelude (
     -- ** Converting from @String@
     ReadS,
     Read(readsPrec, readList),
-    reads, readParen, read, lex, 
-    
+    reads, readParen, read, lex,
+
     -- * Basic Input and output
     IO,
     -- ** Simple I\/O operations
@@ -146,26 +147,24 @@ module Prelude (
 #ifndef __HUGS__
 import Control.Monad
 import System.IO
-import Text.Read
-import Text.Show
+import System.IO.Error
 import Data.List
 import Data.Either
 import Data.Maybe
-import Data.Bool
 import Data.Tuple
 #endif
 
 #ifdef __GLASGOW_HASKELL__
 import GHC.Base
-import GHC.IOBase
-import GHC.Exception
-import GHC.Read
+-- import GHC.IO
+-- import GHC.IO.Exception
+import Text.Read
 import GHC.Enum
 import GHC.Num
 import GHC.Real
 import GHC.Float
 import GHC.Show
-import GHC.Err   ( error, undefined )
+import GHC.Err   ( undefined )
 #endif
 
 #ifdef __HUGS__
@@ -174,12 +173,23 @@ import Hugs.Prelude
 
 #ifndef __HUGS__
 infixr 0 $!
-
+#endif
 
 -- -----------------------------------------------------------------------------
 -- Miscellaneous functions
 
+-- | Strict (call-by-value) application, defined in terms of 'seq'.
 ($!)    :: (a -> b) -> a -> b
+#ifdef __GLASGOW_HASKELL__
+f $! x  = let !vx = x in f vx  -- see #2273
+#elif !defined(__HUGS__)
 f $! x  = x `seq` f x
 #endif
 
+#ifdef __HADDOCK__
+-- | The value of @'seq' a b@ is bottom if @a@ is bottom, and otherwise
+-- equal to @b@.  'seq' is usually introduced to improve performance by
+-- avoiding unneeded laziness.
+seq :: a -> b -> b
+seq _ y = y
+#endif