Functor instance for Set?

Daniel Gorín dgorin at
Thu Mar 1 10:19:39 CET 2012

On Thu, 2012-03-01 at 09:31 +0100, Bas van Dijk wrote:
> On 29 February 2012 19:54, Daniel Gorín <dgorin at> wrote:
> > I was always  under the impression that the fact that Data.Set.Set can not be made an instance of Functor was a sort of unavoidable limitation.
> I guess the way forward is to start using ConstraintKinds and TypeFamilies: [...]

This doesn't really solve the problem I was looking at (namely, making
an ordered-tree-based implementation of a Set type an instance of the
standard Functor class) but I find it very interesting nevertheless. I
need to look at this ConstraintKinds extension in more detail....


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