Module Set

Hi, I think the module Set lacks at least a (partial) function minimum :: forall a. (Ord a) => Set a -> a because "setToList" is the only (though sufficient) function to access the elements of a list. Will "minimum = head . setToList" be correct or do I need to sort the list? I was considering using sorted lists directly, but I thought the functions `elem` and `union` are not as efficient as they could be (under the assumption that the input lists are sorted). Surely balanced trees will be better for large sets. Besides the minimum, also the maximum or the simultaneous splitting of a set into its minimum and the remaining set would be useful (for recursions). Cheers Christian