There was recently a proposal to add indexing operators to Data.Set. Until it is accepted, you can simulate Set with Map like this
import Data.Map type Set a = Map a () Data.Map already has indexing operations (e.g. elemAt, deleteAt). * jwaldmann <waldm...@imn.htwk-leipzig.de> [2012-07-20 13:24:57+0000] > Dear all, > > how would I quickly select an element of a Set (as in Data.Set) > uniformly at random? > > Via the API, this can only be done in linear time? (via toList) > If I could access the tree structure, > then of course it could be logarithmic. > > But probably I'd need a weighted selection sooner or later, > and this would require some specific code anyway. Or does it not? > > Actually I need a sequence of such selections > (each selected element is deleted immediately). > I don't need all elements > (so, computing a random permuation might be too much). > > J.W. > > > > _______________________________________________ > Haskell-Cafe mailing list > Haskell-Cafe@haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe -- Roman I. Cheplyaka :: http://ro-che.info/ _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
