-- Hoogle documentation, generated by Haddock -- See Hoogle, http://www.haskell.org/hoogle/ -- | Deep evaluation of data structures -- @package deepseq @version 1.4.1.0 -- | This module provides an overloaded function, deepseq, for fully -- evaluating data structures (that is, evaluating to "Normal Form"). -- -- A typical use is to prevent resource leaks in lazy IO programs, by -- forcing all characters from a file to be read. For example: -- -- 
--   import System.IO
--   import Control.DeepSeq
--   
--   main = do
--       h <- openFile "f" ReadMode
--       s <- hGetContents h
--       s `deepseq` hClose h
--       return s
--
-- -- deepseq differs from seq as it traverses data structures -- deeply, for example, seq will evaluate only to the first -- constructor in the list: -- -- 
--   > [1,2,undefined] `seq` 3
--   3
--
-- -- While deepseq will force evaluation of all the list elements: -- -- 
--   > [1,2,undefined] `deepseq` 3
--   *** Exception: Prelude.undefined
--
-- -- Another common use is to ensure any exceptions hidden within lazy -- fields of a data structure do not leak outside the scope of the -- exception handler, or to force evaluation of a data structure in one -- thread, before passing to another thread (preventing work moving to -- the wrong threads). -- -- Since: 1.1.0.0 module Control.DeepSeq -- | deepseq: fully evaluates the first argument, before returning -- the second. -- -- The name deepseq is used to illustrate the relationship to -- seq: where seq is shallow in the sense that it only -- evaluates the top level of its argument, deepseq traverses the -- entire data structure evaluating it completely. -- -- deepseq can be useful for forcing pending exceptions, -- eradicating space leaks, or forcing lazy I/O to happen. It is also -- useful in conjunction with parallel Strategies (see the -- parallel package). -- -- There is no guarantee about the ordering of evaluation. The -- implementation may evaluate the components of the structure in any -- order or in parallel. To impose an actual order on evaluation, use -- pseq from Control.Parallel in the parallel -- package. -- -- Since: 1.1.0.0 deepseq :: NFData a => a -> b -> b -- | the deep analogue of $!. In the expression f $!! x, -- x is fully evaluated before the function f is -- applied to it. -- -- Since: 1.2.0.0 ($!!) :: NFData a => (a -> b) -> a -> b -- | a variant of deepseq that is useful in some circumstances: -- -- 
--   force x = x `deepseq` x
--
-- -- force x fully evaluates x, and then returns it. Note -- that force x only performs evaluation when the value of -- force x itself is demanded, so essentially it turns shallow -- evaluation into deep evaluation. -- -- force can be conveniently used in combination with -- ViewPatterns: -- -- 
--   {-# LANGUAGE BangPatterns, ViewPatterns #-}
--   import Control.DeepSeq
--   
--   someFun :: ComplexData -> SomeResult
--   someFun (force -> !arg) = {- 'arg' will be fully evaluated -}
--
-- -- Another useful application is to combine force with -- evaluate in order to force deep evaluation relative to other -- IO operations: -- -- 
--   import Control.Exception (evaluate)
--   import Control.DeepSeq
--   
--   main = do
--     result <- evaluate $ force $ pureComputation
--     {- 'result' will be fully evaluated at this point -}
--     return ()
--
-- -- Since: 1.2.0.0 force :: NFData a => a -> a -- | A class of types that can be fully evaluated. -- -- Since: 1.1.0.0 class NFData a where rnf = grnf . from rnf :: NFData a => a -> () instance [safe] (NFData a1, NFData a2, NFData a3, NFData a4, NFData a5, NFData a6, NFData a7, NFData a8, NFData a9) => NFData (a1, a2, a3, a4, a5, a6, a7, a8, a9) instance [safe] (NFData a1, NFData a2, NFData a3, NFData a4, NFData a5, NFData a6, NFData a7, NFData a8) => NFData (a1, a2, a3, a4, a5, a6, a7, a8) instance [safe] (NFData a1, NFData a2, NFData a3, NFData a4, NFData a5, NFData a6, NFData a7) => NFData (a1, a2, a3, a4, a5, a6, a7) instance [safe] (NFData a1, NFData a2, NFData a3, NFData a4, NFData a5, NFData a6) => NFData (a1, a2, a3, a4, a5, a6) instance [safe] (NFData a1, NFData a2, NFData a3, NFData a4, NFData a5) => NFData (a1, a2, a3, a4, a5) instance [safe] (NFData a, NFData b, NFData c, NFData d) => NFData (a, b, c, d) instance [safe] (NFData a, NFData b, NFData c) => NFData (a, b, c) instance [safe] (NFData a, NFData b) => NFData (a, b) instance [safe] NFData CJmpBuf instance [safe] NFData CFpos instance [safe] NFData CFile instance [safe] NFData CDouble instance [safe] NFData CFloat instance [safe] NFData CSUSeconds instance [safe] NFData CUSeconds instance [safe] NFData CTime instance [safe] NFData CClock instance [safe] NFData CUIntMax instance [safe] NFData CIntMax instance [safe] NFData CUIntPtr instance [safe] NFData CIntPtr instance [safe] NFData CULLong instance [safe] NFData CLLong instance [safe] NFData CSigAtomic instance [safe] NFData CWchar instance [safe] NFData CSize instance [safe] NFData CPtrdiff instance [safe] NFData CULong instance [safe] NFData CLong instance [safe] NFData CUInt instance [safe] NFData CInt instance [safe] NFData CUShort instance [safe] NFData CShort instance [safe] NFData CUChar instance [safe] NFData CSChar instance [safe] NFData CChar instance [safe] NFData Fingerprint instance [safe] NFData Unique instance [safe] NFData ThreadId instance [safe] NFData (StableName a) instance [safe] NFData a => NFData (Product a) instance [safe] NFData a => NFData (Sum a) instance [safe] NFData All instance [safe] NFData Any instance [safe] NFData a => NFData (Last a) instance [safe] NFData a => NFData (First a) instance [safe] NFData a => NFData (Dual a) instance [safe] NFData a => NFData (Down a) instance [safe] (Ix a, NFData a, NFData b) => NFData (Array a b) instance [safe] NFData a => NFData (Const a b) instance [safe] NFData a => NFData (ZipList a) instance [safe] NFData a => NFData [a] instance [safe] NFData Version instance [safe] (NFData a, NFData b) => NFData (Either a b) instance [safe] NFData a => NFData (Maybe a) instance [safe] NFData a => NFData (Complex a) instance [safe] (Integral a, NFData a) => NFData (Ratio a) instance [safe] NFData (a -> b) instance [safe] NFData (Fixed a) instance [safe] NFData (Proxy a) instance [safe] NFData Word64 instance [safe] NFData Word32 instance [safe] NFData Word16 instance [safe] NFData Word8 instance [safe] NFData Int64 instance [safe] NFData Int32 instance [safe] NFData Int16 instance [safe] NFData Int8 instance [safe] NFData () instance [safe] NFData Bool instance [safe] NFData Char instance [safe] NFData Double instance [safe] NFData Float instance [safe] NFData Integer instance [safe] NFData Word instance [safe] NFData Int instance [safe] (GNFData a, GNFData b) => GNFData (a :+: b) instance [safe] (GNFData a, GNFData b) => GNFData (a :*: b) instance [safe] GNFData a => GNFData (M1 i c a) instance [safe] NFData a => GNFData (K1 i a) instance [safe] GNFData U1 instance [safe] GNFData V1