I must say i know very little about the trait system's inner implementation. I am curious if is possible to make builtin traits impls that's not expressable/enumerable in the current language.
I'm imagining a TupleJoin trait
I wonder aside by language internal ugliness, is there anything fundamentally bad about this approach? Because with such a permanently unstable trait defined, i guess we can define a stable and desirable function std::tuple::join: