fact: Fixpoint size_typ (T1 : typ) {struct T1} : nat := match T1 with | typ_base => 1 | typ_arrow T2 T3 => 1 + (size_typ T2) + (size_typ T3) end.
imports: Coq.Logic.FunctionalExtensionality Coq.Program.Equality Metalib.Metatheory Metalib.LibLNgen Stlc