On Wed, 26 Mar 2008, Roman Cheplyaka wrote:
* Andrew Coppin <[EMAIL PROTECTED]> [2008-03-26 12:37:53+0000]
Somebody asked me, so now I'm asking you...
In Haskell, you can make "unboxed" arrays of certain value types. These
are typically more efficient in space, and probably time too, and also
make the array strict in its values. However, you can only do this magic
trick for certain types - not for *all* types.
Why is that? Is it because nobody has done anything about it yet? Is it
because it's thought to be "not necessary" in some way? Is there some
theoretical problem? Has somebody got a better idea?
I did think it was along the lines of "oh, well, if you want to unbox a
type of your own, you just need to write your own instance". The thing
that makes me suspicious of this logic is the absense of an instance for
tuples. Surely this would be trivial to write, and yet it's not present.
If we had instances for a couple of sizes of tuples, it would surely be
quite easy to write your own custom instances that just sit on top of
this and tuple/untuple your custom values...
Any insights here?
Could Data Parallel Haskell[1] be useful for you?
It was designed for parallel computation, but it includes unboxed
arrays, nice list-like syntax and array comprehensions.
1. http://www.haskell.org/haskellwiki/GHC/Data_Parallel_Haskell
A light-weight unboxed array variant is:
http://code.haskell.org/~sjanssen/storablevector/
I thought it might be more efficient sometimes to split, say Word8 and
Double data into two arrays, instead of padding data in order to align a
(Word8,Double) record, but this wouldn't fit into the array data
structure.
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