On Wed, Jul 11, 2007 at 05:45:40PM +0000, Claude Heiland-Allen wrote:
> Hi people,
>
> I'm embedding Haskell into a C program with a "stateful objects with
> message passing" paradigm [0]. I want to make "boxes" with useful
> functions, then connect them together within the C program. I know how to
> build a working version using Data.Dynamic, but that loses polymorphism
> [1].
>
> Say I have 3 boxes:
>
> Box 1: [1,2,5,3] :: [Float]
> Box 2: reverse :: [a] -> [a]
> Box 3: putStrLn . show :: (Show b) => b -> IO ()
>
> I wonder, is it possible to create these boxes separately at runtime (each
> box being compiled/loaded separately with hsplugins), then connect them
> together like {Box 1}=>{Box 2}=>{Box 3} (with a wrapping layer doing
> appropriate type checking/error reporting), or does the whole thing need to
> be compiled statically to generate specialized variants of the polymorphic
> functions? As hinted in #haskell :
>
> <quicksilver> ClaudiusMaximus: I don't think anything will allow you to
> pass around polymorphic values. They're an illusion of the type-checker, in
> a sense.There is nothing intrinsically impossible with a Data.Dynamic like interface for polytypic values. Good luck writing toDyn and fromDyn without compiler support, however. Stefan
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