    {-# OPTIONS_GHC -fno-implicit-prelude #-}
    -----------------------------------------------------------------------------
    -- |
    -- Module      :  Prelude
    -- Copyright   :  (c) The University of Glasgow 2001
    -- License     :  BSD-style (see the file libraries/base/LICENSE)
    --
    -- Maintainer  :  libraries@haskell.org
    -- Stability   :  stable
    -- Portability :  portable
    --
    -- The Prelude: a standard module imported by default into all Haskell
    -- modules.  For more documentation, see the Haskell 98 Report
    -- <http://www.haskell.org/onlinereport/>.
    --
    -----------------------------------------------------------------------------

    module Prelude (

        -- * Standard types, classes and related functions

        -- ** Basic data types
        Bool(False, True),
        (&&), (||), not, otherwise,

        Maybe(Nothing, Just),
        maybe,

        Either(Left, Right),
        either,

        Ordering(LT, EQ, GT),
        Char, String,

        -- *** Tuples
        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
    #endif
    #ifdef __HUGS__
        (:),		-- Not legal Haskell 98
    #endif

        -- ** Basic type classes
        Eq((==), (/=)),
        Ord(compare, (<), (<=), (>=), (>), max, min),
        Enum(succ, pred, toEnum, fromEnum, enumFrom, enumFromThen,
             enumFromTo, enumFromThenTo),
        Bounded(minBound, maxBound),

        -- ** Numbers

        -- *** Numeric types
        Int, Integer, Float, Double,
        Rational,

        -- *** Numeric type classes
        Num((+), (-), (*), negate, abs, signum, fromInteger),
        Real(toRational),
        Integral(quot, rem, div, mod, quotRem, divMod, toInteger),
        Fractional((/), recip, fromRational),
        Floating(pi, exp, log, sqrt, (**), logBase, sin, cos, tan,
                 asin, acos, atan, sinh, cosh, tanh, asinh, acosh, atanh),
        RealFrac(properFraction, truncate, round, ceiling, floor),
        RealFloat(floatRadix, floatDigits, floatRange, decodeFloat,
                  encodeFloat, exponent, significand, scaleFloat, isNaN,
                  isInfinite, isDenormalized, isIEEE, isNegativeZero, atan2),

        -- *** Numeric functions
        subtract, even, odd, gcd, lcm, (^), (^^),
        fromIntegral, realToFrac,

        -- ** Monads and functors
        Monad((>>=), (>>), return, fail),
        Functor(fmap),
        mapM, mapM_, sequence, sequence_, (=<<),

        -- ** Miscellaneous functions
        id, const, (.), flip, ($), until,
        asTypeOf, error, undefined,
        seq, ($!),

        -- * List operations
        map, (++), filter,
        head, last, tail, init, null, length, (!!),
        reverse,
        -- ** Reducing lists (folds)
        foldl, foldl1, foldr, foldr1,
        -- *** Special folds
        and, or, any, all,
        sum, product,
        concat, concatMap,
        maximum, minimum,
        -- ** Building lists
        -- *** Scans
        scanl, scanl1, scanr, scanr1,
        -- *** Infinite lists
        iterate, repeat, replicate, cycle,
        -- ** Sublists
        take, drop, splitAt, takeWhile, dropWhile, span, break,
        -- ** Searching lists
        elem, notElem, lookup,
        -- ** Zipping and unzipping lists
        zip, zip3, zipWith, zipWith3, unzip, unzip3,
        -- ** Functions on strings
        lines, words, unlines, unwords,

        -- * Converting to and from @String@
        -- ** Converting to @String@
        ShowS,
        Show(showsPrec, showList, show),
        shows,
        showChar, showString, showParen,
        -- ** Converting from @String@
        ReadS,
        Read(readsPrec, readList),
        reads, readParen, read, lex,

        -- * Basic Input and output
        IO,
        -- ** Simple I\/O operations
        -- All I/O functions defined here are character oriented.  The
        -- treatment of the newline character will vary on different systems.
        -- For example, two characters of input, return and linefeed, may
        -- read as a single newline character.  These functions cannot be
        -- used portably for binary I/O.
        -- *** Output functions
        putChar,
        putStr, putStrLn, print,
        -- *** Input functions
        getChar,
        getLine, getContents, interact,
        -- *** Files
        FilePath,
        readFile, writeFile, appendFile, readIO, readLn,
        -- ** Exception handling in the I\/O monad
        IOError, ioError, userError, catch

      ) where

    #ifndef __HUGS__
    import Control.Monad
    import System.IO
    import Text.Read
    import Text.Show
    import Data.List
    import Data.Either
    import Data.Maybe
    import Data.Bool
    import Data.Tuple
    import Data.Eq
    import Data.Ord
    #endif

    #ifdef __GLASGOW_HASKELL__
    import GHC.Base
    import GHC.IOBase
    import GHC.Exception
    import GHC.Read
    import GHC.Enum
    import GHC.Num
    import GHC.Real
    import GHC.Float
    import GHC.Show
    import GHC.Err   ( error, undefined )
    #endif

    #ifdef __HUGS__
    import Hugs.Prelude
    #endif

    #ifndef __HUGS__
    infixr 0 $!

    -- -----------------------------------------------------------------------------
    -- Miscellaneous functions

    -- | Strict (call-by-value) application, defined in terms of 'seq'.
    ($!)    :: (a -> b) -> a -> b
    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