I see, thank you for clarification! Kind regards, Nick On Thu, 19 May 2016 at 17:44 David Feuer wrote:

Yes, but no. Once you do that, the whole map is Down. Aside from the inconvenience factor, such a map can't be combined with one in the usual order using union, intersection, etc. We could add conversion functions, but they'd copy the whole structure and really only be special cases of the hypothetical mapKeysDescending. On May 19, 2016 10:40 AM, "Nickolay Kudasov" wrote:

...

Hi David,

Can't this be done simply by using Data.Ord.Down wrapper for the keys?

Kind regards, Nick

On Thu, 19 May 2016 at 17:00 David Feuer wrote:

...

Data.Map offers functions to convert from ascending lists to maps, and also offers a function to map an increasing function over the keys of a map. Equivalents for descending lists and decreasing functions are missing. I think we should add them. Any objections? _______________________________________________ Libraries mailing list Libraries@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/libraries