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-Arra... 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?