applin-ios VS starfx

> Beyond Python and React ... Implementing frontends for other platforms like mobile ...

Shameless plug: I built a mobile version of this: https://www.applin.dev

I built a thing that makes it much simpler to make apps: https://www.applin.dev

You make a web server that returns JSON defining your UI. Then you make a native iOS app by copy/pasting the provided Main.swift file and adding the URL of your server. The app uses an iOS client library, fetches the JSON page definition, and builds/updates the page with native widgets. I'm planning to eventually build Android, web, and desktop clients.

Hi HN, I'm a backend engineer who made an app and didn’t like the tools. Then I made the thing I needed: a mobile app toolkit for backend engineers. I'm calling it Applin™. :)

https://www.applin.dev/

How it works: You make an HTTP server that returns JSON objects that define page content. Then you make a mobile app that calls the server and renders the pages using native widgets. Applin is the server and client libraries that make this easy.

Server libraries: Currently there's Rails https://rubygems.org/gems/applin-rails and https://github.com/leonhard-llc/applin-rails-demo . Which languages shall I add next?

Client libraries: Currently there's iOS https://github.com/leonhard-llc/applin-ios . Which platform shall I add next?

They say, if you're not embarrassed by the quality, then you're launching too late. Applin is usable and not yet pretty and not yet comprehensive. I need customer feedback on priority and requirements.

To try it out right away, use https://apps.apple.com/us/app/applin-tester/id6464230000 and tap the rails-demo link.

The hardest part of this project was making the client update the page without losing keyboard focus and scrolling to the top. To do that, the code must pick the correct existing widgets for each new version of the widget tree. The current (working) version performs five passes over the widget tree: first picking focused widgets and their ancestors, then focus-able widgets, then other stateful widgets, then widgets with matching attributes (label, URL, etc.), and finally former siblings of the correct type. Then it creates any new widgets. Now that it has widgets for the new tree, the code updates the widget tree without removing any sub-widget that will be added again. This prevents losing keyboard focus and prevents resetting scroll positions. Here's the code:

https://github.com/leonhard-llc/applin-ios/blob/main/Sources/ApplinIos/page/widget_cache.swift

Please try out Applin, use it at your company (buy a license), and let me know what features to build first! Post a comment here, add a GitHub issue, or email me at [email protected] .

To get updates, join https://groups.google.com/g/applin-announce .

Thanks for reading! :) --Michael

Ah! A real criticism of FE development, I agree with your problem statement.

When you jump into the world of single-page applications, things get complex pretty quickly, because the use case for needing an SPA pushes the web app into a full desktop application.

Ultimately, for a highly interactive and dynamic "desktop-class" user experience, there is added complexity. I think that's why so much movement within the FE world has moved away from "SPA for everything" and into these mixed dynamic apps. Islands, React Server Components, NextJS, they all help create a middleground between a document-based website with no dynamic elements with a full blown desktop app experience. They all have real tradeoffs, in particular adding an entirely new backend service to serve the front end.

For many projects, react + react-query is probably enough.

Having said that, my argument from https://bower.sh/dogma-of-restful-api still stands: when you build an API that is RESTful (1:1 mapping between endpoint and entity) you are unknowingly pushing the complexity of data synchronization to the FE, which requires a well thought out ETL pipeline.

This probably doesn't help my case but I've been building a simplified middle-layer for react to bridge the gap between react-query and full blown SPA: https://starfx.bower.sh

`redux-saga` maintainer here.

I've been using `effection` to build a replacement for `redux-saga` over at https://github.com/neurosnap/starfx

Effection has demonstrated to me how truly powerful delimited continuations are and why structured concurrency is an incredible asset for anything that requires async flow control -- basically everything in TS/JS.

I know sometimes it's hard to imagine why someone would need structured concurrency or care about delimited continuations for a front-end application, but this is a game changer in terms of expressing async flow control.

Some things to note about Effection:

- API surface area is small https://github.com/thefrontside/effection/issues/851

- It tries to stay as close to JS constructs as possible so it will feel very familiar

- Resource cleanup is automatic (when a function passes out of scope all descendent tasks are shut down automatically)

- End-user doesn't need to think about delimited continuations

The only leap users need to "deal with" coming from async/await is the syntax.

    import { main, call } from "effection";

- https://github.com/thefrontside/continuation

- https://github.com/thefrontside/effection/tree/v3

- https://github.com/neurosnap/starfx

The last one intends to replace redux-saga using DCs.

Here’s a presentation I gave recently talking about DCs in typescript: https://youtu.be/uRbqLGj_6mI?si=XI0JNMKMoO2VHMvM

A couple of us have been experimenting with deliminited continuations and I think it’s gonna take off soon:

https://youtu.be/uRbqLGj_6mI?si=kgKKjpCnehJ9bpIG

https://github.com/neurosnap/starfx

I feel the same way which is why I decided to help maintain the project. Async flow control is very tricky even in js–land. Having watchers live inside of a while-loop is a powerful construct that lends itself to interest flow control patterns.

I'm also in the process of rebuilding redux-saga but without the redux part: https://github.com/neurosnap/starfx

It's still in alpha stage, but it is very reminiscent of redux-saga.