| parallel-1.1.0.1: parallel programming library | Source code | Contents | Index

Control.Parallel.Strategies

Portability | non-portable
Stability | experimental
Maintainer | libraries@haskell.org

Contents

Strategy Type, Application and Semantics
Basic Strategies
Strategic Function Application
Tuples
Lists: Parallel Strategies
Lists: Sequential Strategies
Arrays
Deprecated types and functions

Description
Parallel strategy combinators. See http://www.macs.hw.ac.uk/~dsg/gph/papers/html/Strategies/strategies.html for more information. Original authors: Phil Trinder, Hans-Wolfgang Loidl, Kevin Hammond et al.
Synopsis

type Done = ()
type Strategy a = a -> Done
(>|) :: Done -> Done -> Done
(>||) :: Done -> Done -> Done
using :: a -> Strategy a -> a
demanding :: a -> Done -> a
sparking :: a -> Done -> a
r0 :: Strategy a
rwhnf :: Strategy a
class NFData a where

rnf :: Strategy a

($|) :: (a -> b) -> Strategy a -> a -> b
($||) :: (a -> b) -> Strategy a -> a -> b
(.|) :: (b -> c) -> Strategy b -> (a -> b) -> a -> c
(.||) :: (b -> c) -> Strategy b -> (a -> b) -> a -> c
(-|) :: (a -> b) -> Strategy b -> (b -> c) -> a -> c
(-||) :: (a -> b) -> Strategy b -> (b -> c) -> a -> c
seqPair :: Strategy a -> Strategy b -> Strategy (a, b)
parPair :: Strategy a -> Strategy b -> Strategy (a, b)
seqTriple :: Strategy a -> Strategy b -> Strategy c -> Strategy (a, b, c)
parTriple :: Strategy a -> Strategy b -> Strategy c -> Strategy (a, b, c)
parList :: Strategy a -> Strategy [a]
parListN :: Integral b => b -> Strategy a -> Strategy [a]
parListNth :: Int -> Strategy a -> Strategy [a]
parListChunk :: Int -> Strategy a -> Strategy [a]
parMap :: Strategy b -> (a -> b) -> [a] -> [b]
parFlatMap :: Strategy [b] -> (a -> [b]) -> [a] -> [b]
parZipWith :: Strategy c -> (a -> b -> c) -> [a] -> [b] -> [c]
seqList :: Strategy a -> Strategy [a]
seqListN :: Integral a => a -> Strategy b -> Strategy [b]
seqListNth :: Int -> Strategy b -> Strategy [b]
parBuffer :: Int -> Strategy a -> [a] -> [a]
seqArr :: Ix b => Strategy a -> Strategy (Array b a)
parArr :: Ix b => Strategy a -> Strategy (Array b a)
sPar :: a -> Strategy b
sSeq :: a -> Strategy b
data Assoc a b = a := b
fstPairFstList :: NFData a => Strategy [(a, b)]
force :: NFData a => a -> a
sforce :: NFData a => a -> b -> b

Strategy Type, Application and Semantics

type Done = () | Source

type Strategy a = a -> Done | Source

A strategy takes a value and returns a `Done` value to indicate that the specifed evaluation has been performed.

(>|) :: Done -> Done -> Done | Source

Evaluates the first argument before the second.

(>||) :: Done -> Done -> Done | Source

Evaluates the first argument in parallel with the second.

using :: a -> Strategy a -> a | Source

Takes a value and a strategy, and applies the strategy to the value before returning the value. Used to express data-oriented parallelism. `x `using` s` is a projection on `x`, i.e. both:

a retraction
  `x `using` s` ⊑ `x`
idempotent
  `(x `using` s) `using` s` = `x `using` s`

demanding :: a -> Done -> a | Source

Evaluates the second argument before the first. Used to express control-oriented parallelism. The second argument is usually a strategy application.

sparking :: a -> Done -> a | Source

Evaluates the second argument in parallel with the first. Used to express control-oriented parallelism. The second argument is usually a strategy application.
Basic Strategies

r0 :: Strategy a | Source

Performs no evaluation of its argument.

rwhnf :: Strategy a | Source

Reduces its argument to weak head normal form.

class NFData a where | Source

Methods

rnf :: Strategy a | Source

Reduces its argument to (head) normal form.

Instances

NFData Bool
NFData Char
NFData Double
NFData Float
NFData Int
NFData Int8
NFData Int16
NFData Int32
NFData Int64
NFData Integer
NFData Word8
NFData Word16
NFData Word32
NFData Word64
NFData ()
NFData IntSet
NFData a => NFData ([] a)
(Integral a, NFData a) => NFData (Ratio a)
(RealFloat a, NFData a) => NFData (Complex a)
NFData a => NFData (Maybe a)
NFData a => NFData (IntMap a)
NFData a => NFData (Tree a)
NFData a => NFData (Set a)
(NFData a, NFData b) => NFData (Either a b)
(NFData a, NFData b) => NFData ((,) a b)
(Ix a, NFData a, NFData b) => NFData (Array a b)
(NFData k, NFData a) => NFData (Map k a)
(NFData a, NFData b) => NFData (Assoc a b)
(NFData a, NFData b, NFData c) => NFData ((,,) a b c)
(NFData a, NFData b, NFData c, NFData d) => NFData ((,,,) a b c d)
(NFData a1, NFData a2, NFData a3, NFData a4, NFData a5) => NFData ((,,,,) a1 a2 a3 a4 a5)
(NFData a1, NFData a2, NFData a3, NFData a4, NFData a5, NFData a6) => NFData ((,,,,,) 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)
(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)
(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)

Strategic Function Application

($|) :: (a -> b) -> Strategy a -> a -> b | Source

Sequential function application. The argument is evaluated using the given strategy before it is given to the function.

($||) :: (a -> b) -> Strategy a -> a -> b | Source

Parallel function application. The argument is evaluated using the given strategy, in parallel with the function application.

(.|) :: (b -> c) -> Strategy b -> (a -> b) -> a -> c | Source

Sequential function composition. The result of the second function is evaluated using the given strategy, and then given to the first function.

(.||) :: (b -> c) -> Strategy b -> (a -> b) -> a -> c | Source

Parallel function composition. The result of the second function is evaluated using the given strategy, in parallel with the application of the first function.

(-|) :: (a -> b) -> Strategy b -> (b -> c) -> a -> c | Source

Sequential inverse function composition, for those who read their programs from left to right. The result of the first function is evaluated using the given strategy, and then given to the second function.

(-||) :: (a -> b) -> Strategy b -> (b -> c) -> a -> c | Source

Parallel inverse function composition, for those who read their programs from left to right. The result of the first function is evaluated using the given strategy, in parallel with the application of the second function.
Tuples

seqPair :: Strategy a -> Strategy b -> Strategy (a, b) | Source

Apply two strategies to the elements of a pair sequentially from left to right.

parPair :: Strategy a -> Strategy b -> Strategy (a, b) | Source

Apply two strategies to the elements of a pair in parallel.

seqTriple :: Strategy a -> Strategy b -> Strategy c -> Strategy (a, b, c) | Source

Apply three strategies to the elements of a triple in sequentially from left to right.

parTriple :: Strategy a -> Strategy b -> Strategy c -> Strategy (a, b, c) | Source

Apply three strategies to the elements of a triple in parallel.
Lists: Parallel Strategies

parList :: Strategy a -> Strategy [a] | Source

Applies a strategy to every element of a list in parallel.

parListN :: Integral b => b -> Strategy a -> Strategy [a] | Source

Applies a strategy to the first `n` elements of a list in parallel.

parListNth :: Int -> Strategy a -> Strategy [a] | Source

Evaluates `n` elements of the spine of the argument list and applies the given strategy to the `n`th element (if there is one) in parallel with the result. E.g. `parListNth 2 [e1, e2, e3]` evaluates `e3`.

parListChunk :: Int -> Strategy a -> Strategy [a] | Source

Splits a list into chunks (sub-sequences) of length `n`, and applies a strategy sequentially to the elements in each chunk. The chunks are evaluated in parallel. This is useful for increasing the grain size.

parMap :: Strategy b -> (a -> b) -> [a] -> [b] | Source

Applies a function to each element of a list and and evaluates the result list in parallel, using the given strategy for each element.

parFlatMap :: Strategy [b] -> (a -> [b]) -> [a] -> [b] | Source

Uses `parMap` to apply a list-valued function to each element of a list in parallel, and concatenates the results.

parZipWith :: Strategy c -> (a -> b -> c) -> [a] -> [b] -> [c] | Source

Zips together two lists using a function, and evaluates the result list in parallel.
Lists: Sequential Strategies

seqList :: Strategy a -> Strategy [a] | Source

Sequentially applies a strategy to each element of a list.

seqListN :: Integral a => a -> Strategy b -> Strategy [b] | Source

Sequentially applies a strategy to the first n elements of a list.

seqListNth :: Int -> Strategy b -> Strategy [b] | Source

Applies a strategy to the `n`th element of a list (if there is one) before returning the result. E.g. `seqListNth 2 [e1, e2, e3]` evaluates `e3`.

parBuffer :: Int -> Strategy a -> [a] -> [a] | Source

Applies a strategy to the nth element of list when the head is demanded. More precisely:

- semantics: `parBuffer n s = id :: [a] -> [a]`
- dynamic behaviour: evalutates the nth element of the list when the head is demanded.

The idea is to provide a `rolling buffer' of length n.

`parBuffer` has been added for the revised version of the strategies paper and supersedes the older `fringeList`.

Arrays

seqArr :: Ix b => Strategy a -> Strategy (Array b a) | Source

Apply a strategy to all elements of an array sequentially.

parArr :: Ix b => Strategy a -> Strategy (Array b a) | Source

Apply a strategy to all elements of an array in parallel.
Deprecated types and functions

sPar :: a -> Strategy b | Source

A strategy corresponding to `par`: `x `par` e` = `e `using` sPar x`. `sPar` has been superceded by `sparking`. Replace `e `using` sPar x` with `e `sparking` rwhnf x`.

sSeq :: a -> Strategy b | Source

A strategy corresponding to `seq`: `x `seq` e` = `e `using` sSeq x`. `sSeq` has been superceded by `demanding`. Replace `e `using` sSeq x` with `e `demanding` rwhnf x`.

data Assoc a b | Source

Constructors

a := b |

Instances

(NFData a, NFData b) => NFData (Assoc a b)

fstPairFstList :: NFData a => Strategy [(a, b)] | Source

force :: NFData a => a -> a | Source

sforce :: NFData a => a -> b -> b | Source

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