-- Hoogle documentation, generated by Haddock
-- See Hoogle, http://www.haskell.org/hoogle/
-- | Deep evaluation of data structures
--
-- This package provides methods for fully evaluating data structures
-- ("deep evaluation"). Deep evaluation is often used for adding
-- strictness to a program, e.g. in order to force pending exceptions,
-- remove space leaks, or force lazy I/O to happen. It is also useful in
-- parallel programs, to ensure pending work does not migrate to the
-- wrong thread.
--
-- The primary use of this package is via the deepseq function, a
-- "deep" version of seq. It is implemented on top of an
-- NFData typeclass ("Normal Form Data", data structures with no
-- unevaluated components) which defines strategies for fully evaluating
-- different data types.
--
-- If you want to automatically derive NFData instances via the
-- GHC.Generics facility, there is a companion package
-- deepseq-generics which builds on top of this package.
@package deepseq
@version 1.3.0.2
-- | 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.
--
-- 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 a = a `seq` ()
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] (Ix a, NFData a, NFData b) => NFData (Array a b)
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] (RealFloat a, 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 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