-----------------------------------------------------------------------------
-- |
-- Module      :  Control.DeepSeq
-- Copyright   :  (c) The University of Glasgow 2001-2009
-- License     :  BSD-style (see the file LICENSE)
-- 
-- Maintainer  :  libraries@haskell.org
-- Stability   :  stable
-- Portability :  portable
--
-- Provides an overloaded function 'deepseq' for fully evaluating data
-- structures.
-- 

module DeepSeq (
     NFData(..),
  ) where

import Data.Int
import Data.Word
import Data.Ratio
import Data.Complex
import Data.Map
import Data.Set
import Data.IntMap
import Data.IntSet
import Data.Tree
import Data.Array


-- A class of types that can be fully evaluated.
class NFData a where
    -- | rnf should reduce its argument to normal form (that is, fully
    -- evaluate all sub-components), and then return '()'.
    -- 
    -- The default implementation of 'rnf' is 
    --
    -- > rnf a = a `seq` ()
    -- 
    -- which may be convenient when defining instances for data types with
    -- no unevaluated fields (e.g. enumerations).
    rnf :: a -> ()
    rnf a = a `seq` ()

instance NFData Float

instance NFData a => NFData [a] where
    rnf [] = ()
    rnf (x:xs) = rnf x `seq` rnf xs

instance (NFData a, NFData b) => NFData (a,b) where
  rnf (x,y) = rnf x `seq` rnf y