On 25 April 2015 at 00:01, Henning Thielemann
On Fri, 24 Apr 2015, Ivan Lazar Miljenovic wrote:
Specifically, I have a pull request for fgl [1] to add Ord instances for the graph types (based upon the Ord instances for Data.Map and Data.IntMap, which I believe are themselves partially ordered), and I'm torn as to the soundness of adding these instances.
In an application we needed to do some combinatorics of graphs and thus needed Set Graph.
Nonetheless, I think that graph0 < graph1 should be a type error. We can still have a set of Graphs using a newtype.
This could work; the possible problem would be one of efficiency: if it's done directly on the graph datatypes they can use the underlying (ordered) data structure; going purely by the Graph API, there's no guarantees of ordering and thus it would be needed to call sort, even though in practice it's redundant. -- Ivan Lazar Miljenovic Ivan.Miljenovic@gmail.com http://IvanMiljenovic.wordpress.com