CCing the list back. At Fri, 28 Sep 2012 13:30:52 -0700, Alexander Solla wrote: > What is the problem, exactly? It looks to me like UndecidableInstances and > ScopedTypeVariables (on foo, or its arguments) would be enough.
I'm not sure what you mean. I don't see the need for UndecidableInstances, and there is no way I can see to bring the `b' into scope in the type sig for foo, ScopedTypeVariables or not - unless I'm missing something. > Also note that as stated, foo's type "is a bottom" (more specifically, is a > function onto bottom, since c is free in the class, and so foo must be > parametrically polymorphic in its return type, and so is devoid of "real" > Haskell values). Hopefully that is just an artefact of the translation to > Foo's and Bar's. Yeah the type for `foo' is irrelevant, I just needed to put something there. -- Francesco * Often in error, never in doubt _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
