https://discord.com/channels/280033776820813825/280036215477239809/1139163516159414293

ReifyExceptions.hs

-- code by mniip
types :: [String]
types = $(
  do
    insts <- reifyInstances ''Exception [VarT (mkName "a")]
    let
      tyConOf (AppT ty _) = tyConOf ty
      tyConOf (ConT con) = Just con
      tyConOf _ = Nothing
    tyCons <- for insts \case
      InstanceD _ _ (AppT (ConT exc) ty) _
        | exc == ''Exception
        , Just tyCon <- tyConOf ty
        -> pure tyCon
    Language.Haskell.TH.Syntax.lift $ show <$> filter ((Just "base" ==) . namePackage) tyCons
  )