struct Functor<Type, ReturnType> {
    let method: (Type) -> ReturnType

    func run(_ value: Type) -> ReturnType {
        return method(value)
    }

    func runnable<Ignored>(_ value: Type) -> (Ignored) -> ReturnType {
        return { _ in self.method(value) }
    }
}

extension Functor where Type == Void {
    func run() -> ReturnType {
        return method(())
    }
}