On Thursday 13 October 2005 13:21, Simon Peyton-Jones wrote: > If so, than rather than invent a whole new mechanism, why not simply > extend the existing superclass mechanism to allow a single instance > decl to declare instances for several classes? For example, one add > to Haskell 98 the following: > an instance declaration for a class CD with superclasses C and D > may > give the instances for its superclasses C and D > > [One could quibble about details. E.g Should the class decl for CD > *say* whether the instance decl *must* contain decls for the > superclass methods? Or can one vary it on a instance-by-instance > basis, which might be more flexible?]
I just want to mention Robert Will's proposal for "delayed method definitions"; see http://www.stud.tu-ilmenau.de/~robertw/dessy/fun/ sections 4.3.1 and 4.3.2, which is quite similar to yours. Cheers, Ben _______________________________________________ Haskell mailing list Haskell@haskell.org http://www.haskell.org/mailman/listinfo/haskell
