Jason Dagit <da...@codersbase.com> writes: > On Fri, Apr 30, 2010 at 11:30 PM, Jason Dagit <da...@codersbase.com> wrote: > Looking over this real quick, I think the Graph class should be changed to > mention a and b: > > class Graph (gr a b) where ...
Won't work: you need to specify that gr has kind * -> * -> *; this is exactly the same as how Functor, Monad, etc. are defined. > > Then your instances would be able to mention constraints: > > instance Cls a => Graph (GrB a b) where ... > > Why wasn't the Graph class designed this way? My guess: It was probably a > decision that predated multiparameter type classes. That's not an MPTC (it would be more like "class Graph gr a b" if it was) and doesn't matter in this case anyway. -- Ivan Lazar Miljenovic ivan.miljeno...@gmail.com IvanMiljenovic.wordpress.com _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
