[Haskell-cafe] data type familly and makeLenses

[PICCA Frederic-Emmanuel]

Hello, I defined a typeclass like this with a data familly

class HasConfig a where
  data BinocularsConfig a :: *

  new :: (MonadIO m, MonadLogger m, MonadThrow m) => Maybe FilePath -> m (BinocularsConfig a)
  getConfig :: Maybe FilePath -> IO (Either String (BinocularsConfig a))
  combineWithCmdLineArgs :: BinocularsConfig a -> Maybe ConfigRange -> Maybe (Path Abs Dir) -> BinocularsConfig a
  update :: (MonadIO m, MonadLogger m, MonadThrow m) => FilePath -> m (BinocularsConfig a)

the instance is for now

instance HasConfig PreConfig where
  data BinocularsConfig PreConfig =
    BinocularsPreConfig { _binocularsPreConfigProjectionType :: ProjectionType }
                          deriving (Eq, Show)

   [...]

Since I use Ini to serialize/un-serialize the configuration, I need lens for this type

My question is how can I generate the like easily

makeLenses ''(BinocularsConfig PreConfig) does not work

thanks for considering

Frederic