RxFeedback

TypeScript/JavaScript version of RxFeedback

20min video pitch

The simplest architecture for RxJS

    type FeedbackLoop<State, Event> = 
        (state: rx.Observable<State>) => rx.Observable<Event>;

    type ErrorHandling<State, Event> = {
        // Calculates the new state in case `reduce` throws. Rethrowing terminates the system.
        onReduceError: (state: State, error: any) => State;
        // Applied to the events of every single feedback loop.
        feedbackErrorGuard: (events: rx.Observable<Event>) => rx.Observable<Event>;
    };

    function system<State, Event>(
        initialState: State,
        reduce: (state: State, event: Event) => State,
        feedback: FeedbackLoop<State, Event>[],
        // defaults to `rx.queueScheduler`
        scheduler?: SchedulerLike,
        // defaults to `defaultErrorHandling()`: `reduce` errors are logged to the console
        // and the last good state is kept, feedback loops are retried by using the
        // `defaultRetryStrategy` (exponential backoff, at most 5 seconds between the retries)
        errorHandling?: ErrorHandling<State, Event>
    ): rx.Observable<State>;

Why

• Straightforward

  • If it did happen -> Event
  • If it should happen -> Request
  • To fulfill Request -> Feedback loo

• Declarative

  • System behavior is first declaratively specified and effects begin after subscribe is called => Compile time proof there are no "unhandled states"

• Debugging is easier

  • A lot of logic is just normal pure function that can be debugged using Xcode debugger, or just printing the commands.

• Can be applied on any level

  • Entire system
  • application (state is stored inside a database, CoreData, Firebase, Realm)
  • view controller (state is stored inside system operator)
  • inside feedback loop (another system operator inside feedback loop)

• Works awesome with dependency injection

• Testing

  • Reducer is a pure function, just call it and assert results
  • In case effects are being tested -> TestScheduler

• Can model circular dependencies

• Completely separates business logic from effects (Rx).

  • Business logic can be transpiled between platforms

Installing with NPM

$ npm install rxfeedback

import * as RxFeedback from 'rxfeedback';