fact: Definition _1 {a b : Type} : Lens' (a * b) a := fun _ _ f s => match s with (x, y) => fmap (fun z => (z, y)) (f x) end.
imports: Hask.Prelude Hask.Control.Monad Hask.Data.Functor.Contravariant Hask.Data.Functor.Identity