Perhaps my assumption that TH types directly mirror the internal AST is not correct... A recent user-visible change is in `ConP`
Many TH types are modeled after GHC-internal types, but this is just a matter of convenience, not necessity. (The necessity -- if we are to maintain feature parity in TH -- is that the same information is representable in both sets of types, not that the representations are the same.) So the convention I'm proposing here wouldn't affect TH.