It is fold, although fold is not so great for lists in this context. It's also foldl' union Set.empty, which is better for lists, and probably also for balanced trees. I initially thought that we should surely generalize, but now another alternative comes to mind: remove. As a containers maintainer, I believe we should either: 1. Generalize as proposed, or 2. Deprecate and remove. I'm currently somewhat in favor of the second option. On Feb 3, 2018 9:42 AM, "Henning Thielemann" <lemming@henning-thielemann.de> wrote: On Sat, 3 Feb 2018, Johannes Waldmann wrote: I propose this change for containers:
have: unions :: [ Set a ] -> Set a want: unions :: Foldable f => f (Set a) -> Set a
That's Foldable.fold. _______________________________________________ Libraries mailing list Libraries@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/libraries