Version 21 (modified by Ben Lippmeier, 13 years ago) (diff)


Repa (REgular PArallel arrays)

Repa provides high performance, regular, multi-dimensional, shape polymorphic parallel arrays. All numeric data is stored unboxed. Functions written with the Repa combinators are automatically parallel provided you supply +RTS -Nwhatever on the command line when running the program. Repa means "turnip" in Russian. If you don't like turnips then this library probably isn't for you.


Repa is split up into a few packages to help control dependencies.

If you want the lot then just install the examples, and this will pull down the rest.

cabal install repa-examples

From the source repo

The darcs source repos are at

Report a bug

To report bugs, request features, or get an account on the trac, please send email to


Here is the output of some of the examples included in the repa-examples package:

fft2d-highpass Laplace
more info more info


There is also an OSX demo that does edge detection on a video stream:

video: low(10MB) high(40MB)
  • The source should compile with XCode 3.2.1, GHC 7.0.3 and Repa 2.0.0, but you need to update and run the script to point it to your GHC install.
  • There are also prebuilt OSX i386 versions for two four and six threads. These just have the corresponding +RTS -N# option baked in, you can set it in the main.m module. Some day I will make it so you can select this from the GUI.
  • You can also run the edge detector over a single uncompressed .bmp file using the repa-canny program from the repa-examples package.

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