Discussion so far. There are three aspects of functors that can be "reversed" 1. Foldable-Traversable 2. Applicative 3. Alternative-MonadPlus It appears at first glance that all three of these aspects are independent and thus we would need three different wrappers to implement the three separate functionality. For example lists have all three aspects and one can imagine possibly reversing list instances independently in each of the aspects. So far two name are proposed: Backwards and Reverse. There is one request for not using Reverse because someone want to use it to dualize Ord; however it was suggested that Converse be used for Ord. The question of whether 3 is or isn't independent of the other two is made more difficult due to Alternative/MonadPlus not having a clear set of laws. In fact, MonadPlus has two candidate sets of laws that are not compatible with each other. One possibility is to split this proposal into three proposal, one for each of the aspects. I suggest not doing this, or at least not splitting it up yet, since, although these items appear that they can be applied independently, they are still interrelated as one can see by the fact that the Traversable Reverse instance uses the Applicative Reverse instance. -- Russell O'Connor http://r6.ca/ ``All talk about `theft,''' the general counsel of the American Graphophone Company wrote, ``is the merest claptrap, for there exists no property in ideas musical, literary or artistic, except as defined by statute.''