content: {-# LANGUAGE Trustworthy #-}
  {-# LANGUAGE CPP, NoImplicitPrelude #-}
  {-# OPTIONS_GHC -fno-warn-unused-imports #-}
  -- XXX -fno-warn-unused-imports needed for the GHC.Tuple import below. Sigh.
  
  -----------------------------------------------------------------------------
  -- |
  -- Module      :  Data.Tuple
  -- Copyright   :  (c) The University of Glasgow 2001
  -- License     :  BSD-style (see the file libraries/base/LICENSE)
  -- 
  -- Maintainer  :  libraries@haskell.org
  -- Stability   :  experimental
  -- Portability :  portable
  --
  -- The tuple data types, and associated functions.
  --
  -----------------------------------------------------------------------------
  
  module Data.Tuple
    ( fst         -- :: (a,b) -> a
    , snd         -- :: (a,b) -> a
    , curry       -- :: ((a, b) -> c) -> a -> b -> c
    , uncurry     -- :: (a -> b -> c) -> ((a, b) -> c)
    , swap        -- :: (a,b) -> (b,a)
  #ifdef __NHC__
    , (,)(..)
    , (,,)(..)
    , (,,,)(..)
    , (,,,,)(..)
    , (,,,,,)(..)
    , (,,,,,,)(..)
    , (,,,,,,,)(..)
    , (,,,,,,,,)(..)
    , (,,,,,,,,,)(..)
    , (,,,,,,,,,,)(..)
    , (,,,,,,,,,,,)(..)
    , (,,,,,,,,,,,,)(..)
    , (,,,,,,,,,,,,,)(..)
    , (,,,,,,,,,,,,,,)(..)
  #endif
    )
      where
  
  #ifdef __GLASGOW_HASKELL__
  
  import GHC.Base
  -- We need to depend on GHC.Base so that
  -- a) so that we get GHC.Classes, GHC.Types
  
  -- b) so that GHC.Base.inline is available, which is used
  --    when expanding instance declarations
  
  import GHC.Tuple
  -- We must import GHC.Tuple, to ensure sure that the
  -- data constructors of `(,)' are in scope when we do
  -- the standalone deriving instance for Eq (a,b) etc
  
  #endif  /* __GLASGOW_HASKELL__ */
  
  #ifdef __NHC__
  import Prelude
  import Prelude
    ( (,)(..)
    , (,,)(..)
    , (,,,)(..)
    , (,,,,)(..)
    , (,,,,,)(..)
    , (,,,,,,)(..)
    , (,,,,,,,)(..)
    , (,,,,,,,,)(..)
    , (,,,,,,,,,)(..)
    , (,,,,,,,,,,)(..)
    , (,,,,,,,,,,,)(..)
    , (,,,,,,,,,,,,)(..)
    , (,,,,,,,,,,,,,)(..)
    , (,,,,,,,,,,,,,,)(..)
    -- nhc98's prelude only supplies tuple instances up to size 15
    , fst, snd
    , curry, uncurry
    )
  #endif
  
  default ()              -- Double isn't available yet
  
  -- ---------------------------------------------------------------------------
  -- Standard functions over tuples
  
  #if !defined(__HUGS__) && !defined(__NHC__)
  -- | Extract the first component of a pair.
  fst                     :: (a,b) -> a
  fst (x,_)               =  x
  
  -- | Extract the second component of a pair.
  snd                     :: (a,b) -> b
  snd (_,y)               =  y
  
  -- | 'curry' converts an uncurried function to a curried function.
  curry                   :: ((a, b) -> c) -> a -> b -> c
  curry f x y             =  f (x, y)
  
  -- | 'uncurry' converts a curried function to a function on pairs.
  uncurry                 :: (a -> b -> c) -> ((a, b) -> c)
  uncurry f p             =  f (fst p) (snd p)
  #endif  /* neither __HUGS__ nor __NHC__ */
  
  -- | Swap the components of a pair.
  swap                    :: (a,b) -> (b,a)
  swap (a,b)              = (b,a)
  