Anonymus types in scala example.scala

def offsetMonitor[F[_]: Functor, E, H[_]: Functor, T](
   monitor: H[{def set(offset:Long):Unit}]
 ): Flow[EnvT[E, F, ProducerResult[T]], EnvT[E, F, ProducerResult[T]], NotUsed] =
   Flow[EnvT[E, F, ProducerResult[T]]].map { elem =>
     elem.map { e =>
       monitor.map { m =>
         m.set(e.env.offset)
       }
     }

     elem
   }