Generic middleware

generic_middleware.kt

interface StateWithTopSites : State {
    val topsites: List<TopSite>
}

interface TopSite {
    // ..
}

interface AddTopSiteAction {
    val topSite: TopSite
}

class TopSitesMiddleware<S : StateWithTopSites, A : Action> : Middleware<S, A> {
    override fun invoke(
        context: MiddlewareContext<S, A>,
        next: (A) -> Unit,
        action: A
    ) {
        when (action) {
            is AddTopSiteAction -> TODO("Add to storage")
        }
        
        next(action)
    }
}