hana::sort seems like it should work with hana::experimental::types but does't about hana HOT 3 OPEN

I think the reason types can't be a Sequence is that any implementation of make would lose the run-time information for all of the elements.

For example this would fail:

static_assert(hana::front(hana::make<types_tag>(1, '2', 3.3)) == 1, "");

from hana.

Given the concept of the types container, the expectation is that I cannot hold runtime info, right? It would seem, from my naive perspective, that it should be possible to cleanly disable certain actions without disabling the use of the types container completely.

But perhaps I'm missing a critical insight.

At least conceptually, it's both possible and desirable to be able to sort a type container.

from hana.

It's also possible and desirable to sort a std::vector😛, but for that you would not use hana::sort which works with objects that satisfy hana::Sequence.

I don't know that it is explicitly forbidden. You still have to implement the functions required to make it a Sequence. Here is an example I posted on how to do that: https://stackoverflow.com/a/61879631/800347

I do remember barking up this tree myself and getting shot down. In any case, Boost.Hana is optimized for heterogeneously typed containers that contain run-time information so it is slow for type-only computations compared to libraries such as Boost.Mp11. (It has a sort function.)

from hana.