fact: Definition sum_pred {A B : Type} (PA : A -> Prop) (PB : B -> Prop) : A + B -> Prop := fun x => match x with | inl a => PA a | inr b => PB b end.
imports: Coq(RelationClasses) ExtLib(Structures.Functor Structures.Monad Data.Monads.StateMonad Data.Monads.ReaderMonad Data.Monads.OptionMonad Data.Monads.EitherMonad)