On Fri, Dec 20, 2019 at 10:19 AM Pavel Stehule <pavel.steh...@gmail.com> wrote: > I had a talk with Paul about possible simplification of designed operators. > Last message from Paul was - he is working on new version.
Thanks Alvaro & Pavel for helping move this forward. I've added the casts but they aren't used automatically for things like `range_union(r, mr)` or `mr + r`, even though they are implicit. That's because the casts are for concrete types (e.g. int4range -> int4multirange) but the functions & operators are for polymorphic types (anymultirange + anymultirange). So I'd like to get some feedback about the best way to proceed. Is it permitted to add casts with polymorphic inputs & outputs? Is that something that we would actually want to do? I'd probably need both the polymorphic and concrete casts so that you could still say `int4range(1,2)::int4multirange`. Should I change the coerce code to look for casts among concrete types when the function has polymorphic types? I'm pretty scared to do something like that though, both because of the complexity and lest I cause unintended effects. Should I just give up on implicit casts and require you to specify one? That makes it a little more annoying to mix range & multirange types, but personally I'm okay with that. This is my preferred approach. I have some time over the holidays to work on the other changes Alvaro has suggested. Thanks, Paul
