[Haskell-cafe] Set (Set a) like container - but more efficient?

[Johannes Waldmann]

Marc Weber <marco-oweber <at> gmx.de> writes:

> Does a Set (Set a) like container exist [...]

what do you want to do with this? 
In particular, what methods of the outer set are you planning to use?

Do you perhaps want a disjoint-set representation?
http://stackoverflow.com/questions/15691696/equivalence-classes-and-union-find-in-a-functional-language

- J.W.