Sounds good. I thought something like this could be the solution.
But it might be that my type-knowledge is not good enough - but I have not been
able to do this. Example:
vec1 <- MV.new 1000 :: IO (V.MVector (PrimState IO) Int)
Data.Vector.singleton vec1 -- does not work, gives a lot of type-errs.
Felix
________________________________
Fra: Dmitry Dzhus <d...@dzhus.org>
Til: Fixie Fixie <fixie.fi...@rocketmail.com>; Haskell cafe
<haskell-cafe@haskell.org>
Sendt: Lørdag, 1. desember 2012 12.27
Emne: Re: [Haskell-cafe] Are storable-mutable-vectors in two dimensions
possible in Haskell?
01.12.2012, 15:14, "Fixie Fixie" <fixie.fi...@rocketmail.com>:
> Hello haskellers
> I am struggling with this package: Data.Vector.Storable.Mutable
> I am creating vectors like this: MV.new 1000 :: IO (V.MVector (PrimState IO)
> Int)
> Now I would like access to this vectors in linear time, like I could have
> done in C using pointers.
> The problem is that I do not know which datastructure to keep my vectors in.
> If I put them in a list, the access is very slow. Even a binary tree is very
> slow compared to a C-version.
> I have tried to make an array og vector of storable-mutable vectors, but have
> not manged to accomplish this - even though there must be a haskell way :-)
You can use boxed vector as a first-level structure holding pointers
you your storable vectors to perform O(1) indexing on first dimension.
Alternatively, if your matrix is dense, store your data in a
one-dimensional vector and use Repa as a thin wrapper to perform
multi-dimensional indexing (see toIndex/fromIndex
Data.Array.Repa.Shape).
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