fact: Definition mapWriter (f: pprod A W -> pprod B W') : writer Monoid_W A -> writer Monoid_W' B := mapWriterT Monoid_W' ident B (mkIdent ∘ f ∘ unIdent).
imports: ExtLib.Structures.Monads ExtLib.Structures.Monoid ExtLib.Data.PPair ExtLib.Data.Monads.IdentityMonad Coq.Program.Basics