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The latest version of speculation is 1.5.0.3-0.

speculation

Version 0.6.0 revision 0 uploaded by EdwardKmett.

Package meta

Synopsis
A framework for safe, programmable, speculative parallelism
Description

A framework for safe, programmable, speculative parallelism, loosely based on:

This package provides speculative function application and speculative folds. Speculative STM transactions take the place of the transactional rollback machinery from the paper.

For example:

spec g f a evaluates f g while forcing a, if g == a then f g is returned, otherwise f a is evaluated and returned. Furthermore, if the argument has already been evaluated, we skip the f g computation entirely. If a good guess at the value of a is available, this is one way to induce parallelism in an otherwise sequential task. However, if the guess isn't available more cheaply than the actual answer, then this saves no work and if the guess is wrong, you risk evaluating the function twice.

The best-case timeline looks like:

[---- f g ----]
   [----- a -----]
[-- spec g f a --]

The worst-case timeline looks like:

[---- f g ----]
   [----- a -----]
                 [---- f a ----]
[------- spec g f a -----------]

Compare these to the timeline of f $! a:

[---- a -----]
             [---- f a ----]

specSTM provides a similar time table for STM actions, but also rolls back side-effects.

Changes in 0.6.0:

  • Upgraded the comparisons used by the STM combinators STM actions, so they can check for other STM side-effects.

Changes in 0.5.1:

  • Exposed unsafeGetTagBits and unsafeIsEvaluated

Author
Edward A. Kmett
Bug reports
n/a
Category
Concurrency
Copyright
(c) 2010 Edward A. Kmett
Homepage
http://github.com/ekmett/speculation
Maintainer
Edward A. Kmett <ekmett@gmail.com>
Package URL
n/a
Stability
experimental

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