On Fri, Feb 08, 2002 at 12:39:30PM +0100, Rijk J.C.van Haaften wrote: > Ashley Yakeley wrote: > >I'd like to be able to declare the kinds of new types and synonyms, > >because sometimes Haskell can't infer them. > > It is possible using a trick due to John Hughes. In > Proceedings of the 1999 Haskell Workshop, > he wrote in his article > Restricted Data Types in Haskell > [...] > > data Set cxt a = Set [a] | Unused (cxt a -> ()) deriving Show
Another kludge, that works with newtypes too, is type Hint a b = a newtype Set cxt a = Set (Hint [a] (cxt a)) deriving Show _______________________________________________ Haskell mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell
