Apply lenses to struct

gistfile1.txt

extension Actor {
    struct Lenses {
        static let name = Lens<Actor, String>(
            get: {$0.name},
            set: {(me, value) in Actor(name: value, surname: me.surname) }
        )
        static let surname = Lens<Actor, String>(
            get: {$0.surname},
            set: {(me, value) in Actor(name: me.name, surname: value) }
        )
    }
}

extension Movie {
    struct Lenses {
        static let mainActor = Lens<Movie, Actor?>(get: { movie in
            let actor: Actor? = movie.actors.first
            return actor
        }, set: { me, actor -> Movie in
            guard let actor = actor else { return me }

            return Movie(title: me.title, year: me.year, actors: [actor] + me.actors)
        })
    }
}