So IIUC the difference that we're talking about is the following:
...
consteval string_view my_algo(meta::info mo) {
return classify(type_identity<do_t<something_t<here_t<[: mo :]>>>>{});
}
This code is incorrect : "mo" here is not an instantiation-time value and so cannot be spliced.
As for the rest of your concerns, I'd like to emphasize that, since it's easy to transform one style of API into the other at a library level, there are no fundamental differences between the two, except that the TMP-based reflection will take more of the compiler resources.
I've spent the last week playing with the value-based implementation (and also with meta::info a little) and I think my confusion came from having heard and read that the consteval API tries to replace template-based API. IIUC that is not true in many cases and instantiation is required to some parts of meta::info to work.
I might implement the reflection TS as a library using clang-meta, to illustrate the point.
I see now how that might be doable with the splicing operators working differently in templates than in plain consteval functions.
I hope I'll be useful to gather the use-cases that we need to cover with the standardized API, find common patterns, identify potantial higher-level utilities, etc.
PRs with new examples and feedback is welcome.
--Matus