Hi @mtth
Did you have an opportunity to have a look at this PR? :)

Hi @JakubBarta, apologies for the delay. I'm concerned that this change will restrict our ability to evolve the library. For example #13 might have broken clients if they relied on the type's representation. I understand the usefulness of being able to define new instances but I'm not sure what a good solution to allow it is yet.

Could you share the instance MonadBaseControl instance implementation you'd use?

Hi @mtth, thanks for the quick reply!
I actually had to define instances for multiple typeclasses. Most of them are derived:

deriving newtype instance MonadBaseControl IO m => MonadBaseControl IO (TraceT m)
deriving newtype instance MonadBase IO m => MonadBase IO (TraceT m)
deriving newtype instance MonadMask m => MonadMask (TraceT m)
deriving newtype instance MonadThrow m => MonadThrow (TraceT m)
deriving newtype instance MonadFail m => MonadFail (TraceT m)
deriving newtype instance (MonadCatch m, MonadThrow m) => MonadCatch (TraceT m)