You might also look at how Data Parallel Haskell implements its arrays. IIRC, it implements an array of n-field records as n arrays. You can easily do that with typeclasses and type families.
2009/11/11 Tillmann Vogt <tillmann.v...@rwth-aachen.de>: > Hi, > > I tried to use unboxed arrays for generating an antialiased texture. To make > it easier to understand, here is the stripped down code that produces an > error: > >>import Control.Monad.ST >>import Data.Array.ST >>import Data.Array.Unboxed >>import Data.Word >>type BitMask = UArray Int Word16 -- for determining the grey value of a >> pixel >>type Pixels = (Int, Int, T) >>data T = N | B BitMask -- this does not work >>-- type T = Int -- this works if int the next line N is replaced by ..lets >> say 0 >>f = newArray (0,10) N :: (ST s (STUArray s Int T)) > > http://hackage.haskell.org/packages/archive/array/0.2.0.0/doc/html/Data-Array-MArray.html#t%3AMArray > shows that mutable/unboxed arrays only allow simple types: > i.e. MArray (STUArray s) Int32 (ST s) > > Isn't this ugly? Imagine this would be the case in C: > > > struct stupidArrayElement{ > int a; > int b; // not allowed! > } > > stupidArrayElement s[10]; > > > Wouldn't it be nice to have something like: MArray (STUArray s) e (ST s) > with e being a non-recursive data type (like data T = N | B Bitmask). > My understanding of Haskell isn't deep enough to know if I have overlooked > something or if the problem is solvable without a language extension. With a > language extension I guess that it is not hard to find out if an abstract > data type is non-recursive. Then this type should be serializable > automatically. > > What do you think? > _______________________________________________ > Haskell-Cafe mailing list > Haskell-Cafe@haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe > -- Eugene Kirpichov Web IR developer, market.yandex.ru _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe