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