I agree; the problem is that I fear that making my own instance by using setToList will be very inefficient (or at least much more so than an instance which actually looks at the tree structure).
-- Hal Daume III "Computer science is no more about computers | [EMAIL PROTECTED] than astronomy is about telescopes." -Dijkstra | www.isi.edu/~hdaume On Wed, 29 May 2002, Johannes Waldmann wrote: > > for instance, Sets of Sets of things would be really nice. > > Sure. One could simply use lexicographic ordering > (i. e. s1 `compare` s2 = setToList s1 `compare` setToList s2) > or length-lexicographic ordering (for efficiency) > ... = (cardinality s1, setToList s1) `compare` (cardinality s2, setToList s2) > > As you write, there seems to be no reason not to do this. > An Ord instance should be a linear ordering, and the above are. > -- > -- Johannes Waldmann ---- http://www.informatik.uni-leipzig.de/~joe/ -- > -- [EMAIL PROTECTED] -- phone/fax (+49) 341 9732 204/252 -- > _______________________________________________ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users