Sebastian Fischer
Furthermore, as I said earlier, it doesn't make sense to constrain the label type just to make an instance of a type class.
(Now, if we had other functions in there which _might_ depend on the label types, this _would_ make sense; as it stands however, it doesn't.)
You'll notice that my empty does depend on a having a Cls instance because it will fail to compile. [...] I'm not understanding your point, and I suspect you're not understanding mine :)
Let's assume he did understand your point. I think Ivan doubt's that there is any real need for the change because (while defining the set monad may make sense) "it does not make sense" to wish for being able to use additional constraints when defining the specific functions that are currently in the Graph class.
My objections were that there are no ways any such Graph instance would/should use any of the label values when defining definitions for the various methods; the labels are just meant to be extra things _attached_ to the nodes and edges.
I'm not sure if I agree. It would be interesting to see whether the real graph behind the original problem is an example where such additional constraints are really necessary and make sense.
Well, yes, having Kevin actually responding back would help ;-) -- Ivan Lazar Miljenovic Ivan.Miljenovic@gmail.com IvanMiljenovic.wordpress.com