Safe Haskell	Safe
Language	Haskell98

Control.Monad.Par.Class

Contents

Futures
IVars

Description

This module establishes a class hierarchy that captures the interfaces of Par monads. There are two layers: simple futures (ParFuture) and full IVars (ParIVar). All Par monads are expected to implement the former, some also implement the latter.

For more documentation of the programming model, see

The Control.Monad.Par module in the monad-par package.
The wiki/tutorial (http://www.haskell.org/haskellwiki/Par_Monad:_A_Parallelism_Tutorial)
The original paper (http://www.cs.indiana.edu/~rrnewton/papers/haskell2011_monad-par.pdf)
Tutorial slides (http://community.haskell.org/~simonmar/slides/CUFP.pdf)
Other slides (http://www.cs.ox.ac.uk/ralf.hinze/WG2.8/28/slides/simon.pdf, http://www.cs.indiana.edu/~rrnewton/talks/2011_HaskellSymposium_ParMonad.pdf)

Synopsis

Futures

class Monad m => ParFuture future m | m -> future where #

ParFuture captures the class of Par monads which support futures. This level of functionality subsumes par/pseq and is similar to the Control.Parallel.Strategies.Eval monad.

A minimal implementation consists of spawn_ and get. However, for monads that are also a member of ParIVar it is typical to simply define spawn in terms of fork, new, and put.

Minimal complete definition

spawn_, get

Methods

spawn :: NFData a => m a -> m (future a) #

Create a potentially-parallel computation, and return a future (or promise) that can be used to query the result of the forked computataion.

 spawn p = do
   r <- new
   fork (p >>= put r)
   return r

spawn_ :: m a -> m (future a) #

Like spawn, but the result is only head-strict, not fully-strict.

get :: future a -> m a #

Wait for the result of a future, and then return it.

spawnP :: NFData a => a -> m (future a) #

Spawn a pure (rather than monadic) computation. Fully-strict.

 spawnP = spawn . return

IVars

class ParFuture ivar m => ParIVar ivar m | m -> ivar where #

ParIVar builds on futures by adding full anyone-writes, anyone-reads IVars. These are more expressive but may not be supported by all distributed schedulers.

A minimal implementation consists of fork, put_, and new.

Minimal complete definition

fork, new, put_

Methods

fork :: m () -> m () #

Forks a computation to happen in parallel. The forked computation may exchange values with other computations using IVars.

new :: m (ivar a) #

creates a new IVar

put :: NFData a => ivar a -> a -> m () #

put a value into a IVar. Multiple puts to the same IVar are not allowed, and result in a runtime error.

put fully evaluates its argument, which therefore must be an instance of NFData. The idea is that this forces the work to happen when we expect it, rather than being passed to the consumer of the IVar and performed later, which often results in less parallelism than expected.

Sometimes partial strictness is more appropriate: see put_.

put_ :: ivar a -> a -> m () #

like put, but only head-strict rather than fully-strict.

newFull :: NFData a => a -> m (ivar a) #

creates a new IVar that contains a value

newFull_ :: a -> m (ivar a) #

creates a new IVar that contains a value (head-strict only)

class NFData a #

A class of types that can be fully evaluated.

Since: 1.1.0.0

Instances

NFData Bool
Methods rnf :: Bool -> () #
NFData Char
Methods rnf :: Char -> () #
NFData Double
Methods rnf :: Double -> () #
NFData Float
Methods rnf :: Float -> () #
NFData Int
Methods rnf :: Int -> () #
NFData Int8
Methods rnf :: Int8 -> () #
NFData Int16
Methods rnf :: Int16 -> () #
NFData Int32
Methods rnf :: Int32 -> () #
NFData Int64
Methods rnf :: Int64 -> () #
NFData Integer
Methods rnf :: Integer -> () #
NFData Word
Methods rnf :: Word -> () #
NFData Word8
Methods rnf :: Word8 -> () #
NFData Word16
Methods rnf :: Word16 -> () #
NFData Word32
Methods rnf :: Word32 -> () #
NFData Word64
Methods rnf :: Word64 -> () #
NFData CallStack	Since: 1.4.2.0
Methods rnf :: CallStack -> () #
NFData TypeRep	NOTE: Only defined for `base-4.8.0.0` and later Since: 1.4.0.0
Methods rnf :: TypeRep -> () #
NFData ()
Methods rnf :: () -> () #
NFData TyCon	NOTE: Only defined for `base-4.8.0.0` and later Since: 1.4.0.0
Methods rnf :: TyCon -> () #
NFData Natural	Since: 1.4.0.0
Methods rnf :: Natural -> () #
NFData Void	Defined as `rnf = absurd`. Since: 1.4.0.0
Methods rnf :: Void -> () #
NFData Version	Since: 1.3.0.0
Methods rnf :: Version -> () #
NFData Unique	Since: 1.4.0.0
Methods rnf :: Unique -> () #
NFData ThreadId	Since: 1.4.0.0
Methods rnf :: ThreadId -> () #
NFData ExitCode	Since: 1.4.2.0
Methods rnf :: ExitCode -> () #
NFData CChar	Since: 1.4.0.0
Methods rnf :: CChar -> () #
NFData CSChar	Since: 1.4.0.0
Methods rnf :: CSChar -> () #
NFData CUChar	Since: 1.4.0.0
Methods rnf :: CUChar -> () #
NFData CShort	Since: 1.4.0.0
Methods rnf :: CShort -> () #
NFData CUShort	Since: 1.4.0.0
Methods rnf :: CUShort -> () #
NFData CInt	Since: 1.4.0.0
Methods rnf :: CInt -> () #
NFData CUInt	Since: 1.4.0.0
Methods rnf :: CUInt -> () #
NFData CLong	Since: 1.4.0.0
Methods rnf :: CLong -> () #
NFData CULong	Since: 1.4.0.0
Methods rnf :: CULong -> () #
NFData CLLong	Since: 1.4.0.0
Methods rnf :: CLLong -> () #
NFData CULLong	Since: 1.4.0.0
Methods rnf :: CULLong -> () #
NFData CFloat	Since: 1.4.0.0
Methods rnf :: CFloat -> () #
NFData CDouble	Since: 1.4.0.0
Methods rnf :: CDouble -> () #
NFData CPtrdiff	Since: 1.4.0.0
Methods rnf :: CPtrdiff -> () #
NFData CSize	Since: 1.4.0.0
Methods rnf :: CSize -> () #
NFData CWchar	Since: 1.4.0.0
Methods rnf :: CWchar -> () #
NFData CSigAtomic	Since: 1.4.0.0
Methods rnf :: CSigAtomic -> () #
NFData CClock	Since: 1.4.0.0
Methods rnf :: CClock -> () #
NFData CTime	Since: 1.4.0.0
Methods rnf :: CTime -> () #
NFData CUSeconds	Since: 1.4.0.0
Methods rnf :: CUSeconds -> () #
NFData CSUSeconds	Since: 1.4.0.0
Methods rnf :: CSUSeconds -> () #
NFData CFile	Since: 1.4.0.0
Methods rnf :: CFile -> () #
NFData CFpos	Since: 1.4.0.0
Methods rnf :: CFpos -> () #
NFData CJmpBuf	Since: 1.4.0.0
Methods rnf :: CJmpBuf -> () #
NFData CIntPtr	Since: 1.4.0.0
Methods rnf :: CIntPtr -> () #
NFData CUIntPtr	Since: 1.4.0.0
Methods rnf :: CUIntPtr -> () #
NFData CIntMax	Since: 1.4.0.0
Methods rnf :: CIntMax -> () #
NFData CUIntMax	Since: 1.4.0.0
Methods rnf :: CUIntMax -> () #
NFData All	Since: 1.4.0.0
Methods rnf :: All -> () #
NFData Any	Since: 1.4.0.0
Methods rnf :: Any -> () #
NFData Fingerprint	Since: 1.4.0.0
Methods rnf :: Fingerprint -> () #
NFData SrcLoc	Since: 1.4.2.0
Methods rnf :: SrcLoc -> () #
NFData a => NFData [a]
Methods rnf :: [a] -> () #
NFData a => NFData (Maybe a)
Methods rnf :: Maybe a -> () #
NFData a => NFData (Ratio a)
Methods rnf :: Ratio a -> () #
NFData (Ptr a)	Since: 1.4.2.0
Methods rnf :: Ptr a -> () #
NFData (FunPtr a)	Since: 1.4.2.0
Methods rnf :: FunPtr a -> () #
NFData a => NFData (Identity a)	Since: 1.4.0.0
Methods rnf :: Identity a -> () #
NFData a => NFData (Min a)	Since: 1.4.2.0
Methods rnf :: Min a -> () #
NFData a => NFData (Max a)	Since: 1.4.2.0
Methods rnf :: Max a -> () #
NFData a => NFData (First a)	Since: 1.4.2.0
Methods rnf :: First a -> () #
NFData a => NFData (Last a)	Since: 1.4.2.0
Methods rnf :: Last a -> () #
NFData m => NFData (WrappedMonoid m)	Since: 1.4.2.0
Methods rnf :: WrappedMonoid m -> () #
NFData a => NFData (Option a)	Since: 1.4.2.0
Methods rnf :: Option a -> () #
NFData a => NFData (NonEmpty a)	Since: 1.4.2.0
Methods rnf :: NonEmpty a -> () #
NFData (Fixed a)	Since: 1.3.0.0
Methods rnf :: Fixed a -> () #
NFData a => NFData (Complex a)
Methods rnf :: Complex a -> () #
NFData (StableName a)	Since: 1.4.0.0
Methods rnf :: StableName a -> () #
NFData a => NFData (ZipList a)	Since: 1.4.0.0
Methods rnf :: ZipList a -> () #
NFData a => NFData (Dual a)	Since: 1.4.0.0
Methods rnf :: Dual a -> () #
NFData a => NFData (Sum a)	Since: 1.4.0.0
Methods rnf :: Sum a -> () #
NFData a => NFData (Product a)	Since: 1.4.0.0
Methods rnf :: Product a -> () #
NFData a => NFData (First a)	Since: 1.4.0.0
Methods rnf :: First a -> () #
NFData a => NFData (Last a)	Since: 1.4.0.0
Methods rnf :: Last a -> () #
NFData (IORef a)	NOTE: Only strict in the reference and not the referenced value. Since: 1.4.2.0
Methods rnf :: IORef a -> () #
NFData a => NFData (Down a)	Since: 1.4.0.0
Methods rnf :: Down a -> () #
NFData (MVar a)	NOTE: Only strict in the reference and not the referenced value. Since: 1.4.2.0
Methods rnf :: MVar a -> () #
NFData (a -> b)	This instance is for convenience and consistency with `seq`. This assumes that WHNF is equivalent to NF for functions. Since: 1.3.0.0
Methods rnf :: (a -> b) -> () #
(NFData a, NFData b) => NFData (Either a b)
Methods rnf :: Either a b -> () #
(NFData a, NFData b) => NFData (a, b)
Methods rnf :: (a, b) -> () #
(NFData a, NFData b) => NFData (Array a b)
Methods rnf :: Array a b -> () #
(NFData a, NFData b) => NFData (Arg a b)	Since: 1.4.2.0
Methods rnf :: Arg a b -> () #
NFData (Proxy k a)	Since: 1.4.0.0
Methods rnf :: Proxy k a -> () #
NFData (STRef s a)	NOTE: Only strict in the reference and not the referenced value. Since: 1.4.2.0
Methods rnf :: STRef s a -> () #
(NFData a, NFData b, NFData c) => NFData (a, b, c)
Methods rnf :: (a, b, c) -> () #
NFData a => NFData (Const k a b)	Since: 1.4.0.0
Methods rnf :: Const k a b -> () #
(NFData a, NFData b, NFData c, NFData d) => NFData (a, b, c, d)
Methods rnf :: (a, b, c, d) -> () #
(NFData a1, NFData a2, NFData a3, NFData a4, NFData a5) => NFData (a1, a2, a3, a4, a5)
Methods rnf :: (a1, a2, a3, a4, a5) -> () #
(NFData a1, NFData a2, NFData a3, NFData a4, NFData a5, NFData a6) => NFData (a1, a2, a3, a4, a5, a6)
Methods rnf :: (a1, a2, a3, a4, a5, a6) -> () #
(NFData a1, NFData a2, NFData a3, NFData a4, NFData a5, NFData a6, NFData a7) => NFData (a1, a2, a3, a4, a5, a6, a7)
Methods rnf :: (a1, a2, a3, a4, a5, a6, a7) -> () #
(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)
Methods rnf :: (a1, a2, a3, a4, a5, a6, a7, a8) -> () #
(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)
Methods rnf :: (a1, a2, a3, a4, a5, a6, a7, a8, a9) -> () #