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arrayshaskellmulticorevectorization

Which haskell array implementation to use? AKA what are the pros and cons of each

What do I need? [an unordered list]

  • VERY easy parallelization
  • support for map, filter etc.
  • ability to perform array based computations efficiently, like A=B+C, sort of like matlab arrays.
  • Generation of SIMD code. I guess this is out of the question in the near future for anything, but hey, I can ask :)
  • support for matrices should be there at a minimum, higher dimensions are lower priority right now.
  • ability to get a pointer to it and create one from a C pointer.
  • Support from other libraries. IE, bindings to popular C math packages, i/o to disk or images if the arrays are 2D

What do I see?

  • Array package in haskell-platform. It's the blessed one and can do parallel
  • Data.Vector. Has loop fusion, but not in platform, so its maturity is unknown to me.
  • repa package, contributed by the DPH team, but doesn't work well with any stable ghc today.
  • Lots of variation in the level of support for array implementations. For instance, there doesn't seem to be an easy way to dump a 2D vector to a image file. IOW, the haskell community apparently hasn't settled on an array implementation.

So please, help me choose.

EDIT A=B+C refers to element wise addition, and not list concatenation

Solution

  • Correct, the community hasn't settled on a good array implementation. I think it would be a good Haskell Prime submission to put forward the Vector API and remove Data.Array.

    Vector is very mature! It has:

    • VERY easy parallelization
    • support for map, filter etc.
    • performs array based computations efficiently, like A=B+C (but I'm not in tune with how matlab does it)
    • vector creation from a pointer via Vector.Storable

    It does not:

    • have enough support from other libraries. IE, bindings to popular C math packages
    • support matrices, but you can have vectors of vectors. If you build some vector-based matrix operations then perhaps you could upload to hackage as vector-matrix.
    • Generate SIMD code.

    NOTE: You can turn bytestrings into vectors of whatever, so if you have an image as a bytestring then, via Vector.Storable, you might be able to do what you want with the image as a vector.