Re: [Haskell-cafe] Implementing fixed-sized vectors (using datatype algebra?)

On Thu, 31 Jan 2008, Alfonso Acosta wrote:

On Jan 31, 2008 3:03 PM, Wolfgang Jeltsch wrote:

...

Hello Fons,

interestingly, it occured to me yesterday that the graphics part of Grapefruit would benefit from fixed sized vectors. I think we should implement some small Cabal package which just provides this and upload it to the HackageDB. Are you interested in cooperating with me on this?

Sure I am!

Actually, thanks to the pointers provided by Henning I learned that Oleg (who else!) already has implemented them. See

http://okmij.org/ftp/Haskell/number-parameterized-types.html http://www.haskell.org/tmrwiki/NumberParamTypes http://okmij.org/ftp/Haskell/number-param-vector-code.tar.gz (Oleg's multiple flavour implementations of fixed-sized vectors)

I think we should base our implementation on Oleg's (for which we need his permission). Actually, I think we should create two separate libraries. One for decimal type-level arithmetic

I remember that type-level arithmetic is already implemented somewhere, certainly more than once, but certainly seldom in a nicely packaged form. erm, here http://www.haskell.org/haskellwiki/Type_arithmetic http://www.haskell.org/ghc/docs/latest/html/libraries/base/Data-Fixed.html#t... also here: http://hackage.haskell.org/cgi-bin/hackage-scripts/package/numbers-2007.9.25 ?