$\lambda$Prolog is known to be well-suited for expressing and implementing logics and inference systems. We show that lemmas and definitions in such logics can be implemented with a great economy of expression. We encode a higher-order logic using an encoding that maps both terms and types of the object logic (higher-order logic) to terms of the metalanguage ($\lambda$Prolog). We discuss both the Terzo and Teyjus implementations of $\lambda$Prolog. We also encode the same logic in Twelf and compare the features of these two metalanguages for our purposes.