The speculation package

A framework for safe, programmable, speculative parallelism, loosely based on http://research.microsoft.com/pubs/118795/pldi026-vaswani.pdf

spec g f a evaluates f g while forcing a, if g == a then f g is returned. Otherwise f a is evaluated.

Furthermore, if the argument has already been evaluated, we avoid sparking the parallel computation at all.

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.

 spec a f a = a `seq` f a

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 -----------]

Compared to the unspeculated timeline of

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

Changes since 0.0.1

specFoldr1 bug fix
Added spec' combinator

Changes since 0.0.0

Added WithoutSpeculation and WrappedFoldable

Properties

Versions	0.0.0, 0.0.1, 0.0.2, 0.1.0, 0.2.0, 0.3.0, 0.4.0, 0.5.0, 0.5.1, 0.6.0, 0.7.0, 0.8.0, 0.8.0.1, 0.8.0.2, 0.8.1.0, 0.8.2.0, 0.9.0.0, 1.0.0.0, 1.1.0.0, 1.2.0.0, 1.2.0.1, 1.2.0.2, 1.3, 1.4, 1.4.1, 1.4.1.1, 1.4.1.2
Dependencies	array (≥0.2 & <0.4), base (≥4 & <6), containers (≥0.2.0.1), parallel (2.2.*)
License	BSD3
Copyright	(c) 2010 Edward A. Kmett
Author	Edward A. Kmett
Maintainer	Edward A. Kmett <ekmett@gmail.com>
Stability	experimental
Category	Concurrency
Home page	http://github.com/ekmett/speculation
Upload date	Sun Jun 27 08:20:09 UTC 2010
Uploaded by	EdwardKmett
Built on	ghc-6.12

Modules

Control
- Concurrent
  - Control.Concurrent.Speculation

Downloads

speculation-0.0.2.tar.gz (Cabal source package)
package description (included in the package)