fact: Definition castWriterT : writerT Monoid_W m A -> writerT Monoid_W' m A := mkWriterT Monoid_W' ∘ runWriterT.
imports: ExtLib.Structures.Monads ExtLib.Structures.Monoid ExtLib.Data.PPair ExtLib.Data.Monads.IdentityMonad Coq.Program.Basics