Show HN: Rust GUI Library via Flutter (opens in new tab)

Flutter is not bad, but I hesitate diving into it based upon who controls it. Using a Google product feels like you're in constant threat of it just disappearing.

It also still has all the remnants of mobile and fingers and not desktop and mouse. Support for improving this is non-existent in my experience.

> I know Flutter/Dart doesn't get much love here on HN but in my opinion I think it's much easier to reason about than a system like React which I think is the wrong level of abstraction compared to Flutter's render the entire widget tree approach.

Could you expand on this a bit? My impression was that Flutter and React had relatively similar approaches to components, but I haven't had much experience with Flutter yet, so I'm interested to hear your experiences!

But, Flutter and React work the same way where UI is a function of state. In fact, Flutter started off imperatively but after React was released, they changed it to be declarative, and now Android via Jetpack Compose is changing to be declarative, all on the same general principle. I also use packages like flutter_hooks or ReArch which make encapsulating state much easier, I couldn't stand using initState and not forgetting to dispose for each piece of functionality.

You are welcome, and happy to hear it works for you!

> I know Flutter/Dart doesn't get much love here on HN but in my opinion I think it's much easier to reason about than a system like React which I think is the wrong level of abstraction compared to Flutter's render the entire widget tree approach.

Yeah I really like Flutter/Dart. I had less an issue with React itself than I did the whole HTML/CSS/Javascript ecosystem and tooling. Flutter is a breath of fresh air in that it is a purpose built ecosystem for UIs. You load the SDK and are ready to go with features like hot reload out of the box. No need for gamut of tools and to figure out how they all work together. Also, no need for HTML + CSS! I think the only reason it isn't more popular is because we have such a huge # of frontend devs already trained on HTML/CSS/JS, as Flutter is a lot simpler out of the gate, and much easier for traditional GUI paradigm people IMO.

Just want to say, your site is very aesthetically pleasing. I hate blue websites (FB Blue) -- but the deep tones that SOS uses and contrasts are really appealing.

So is the app, subscribed.

Looks nice. What UI design system did you use here if I can ask?

You are welcome, and I am happy to see it helps! When I initially develop flutter_rust_bridge, my personal usage scenario is quite similar to yours: using Rust for some high performance algorithms.

Thank you! I heard some people saying that, for apps using JavaScript, Tauri is replacing Electron and is popular nowadays, since Electron is very widely used. It seems Tauri cannot let Rust communicate with JavaScript very seamlessly yet, e.g. https://tauri.app/v1/guides/features/command/ seems to have mainly basic features. oneshtein mentioned below that Tauri does not support mobile as first class citizen yet as well. Looking forward to seeing Tauri's bridge to improve and supporting mobile better in the future!

From what I can tell. I've not used Tauri and it's been years since I've tried flutter.

Tauri currently has poor support for mobile and Linux (because of the state of WebkitGtk).

Flutter uses Dart which is not widely used for anything else. Harder to learn as there is no MDN, w3schools or standard spec for it. Also Flutter Web has issues due to it's use of Canvas over the DOM.

IMO, electron is still the way to go for cross platform apps.

Thanks! Shortly speaking, the Rust code is parsed (e.g. "here is a function and there is a struct"), and then some Rust and Flutter code are generated. As for comparison, some pros and cons are discussed in the blog.

For app size, it depends on your specific scenario, because e.g. Flutter automatically removes library code that is not used. I remembered (but the memory is blur) simple app has something like ~5MB. Btw remember to split .so file per abi. For UI performance, I personally find it quite good, and Flutter(Dart) is compiled to assembly code via AOT (instead of e.g. JIT or interpreted), which theoretically speaking is also fast. For both, I would suggest to make a demo for your specific case to have more accurate results. Also I guess ask/discuss on the Flutter community may help.

Do you mean in Flutter generally? I'd say it's very good, easy to build in on widget by widget basis, very easy to check and rest when running builds.

Do you run a gRPC service on the desktop where the UI runs, and connect the 2 via localhost?

Thank you!

Qt has some commercial license only components, but the majority is open-source. In fact, the KDE Free Qt Foundation ensures that the framework is always available under GPL+LGPLv3.[0]

Anyway, there are some languages specifically desgined for making UIs. Qt has one of those, QML[1]. It's a "simple" language made precisely for UI development, that can be wired to C++, allowing you to write business logic in a general language, while keeping UI focused.

More interestingly, though, is Slint[2]. The language (and company behind it) was made by ex-QML devs which sought to improve the design, avoiding some pitfalls that QML ended up running into. It's core is written in Rust, but there are bindings for C++, JS and now Python too. They also have a focus on embedded devices, which ends up translating to always having good performance and memory footprint in mind, which is neat.

One of Slint's dev is ogoffart: https://news.ycombinator.com/user?id=ogoffart

[0]: https://www.qt.io/faq/tag/qt-open-source-licensing [1]: https://en.wikipedia.org/wiki/QML [2]: https://slint.dev

XAML is very much alive within Avalonia[0], Uno[1] and MAUI[2] (not to mention WPF) :)

There is support and growing popularity for declarative UI defined in C#[3] and F#[4] instead though.

[0]: https://docs.avaloniaui.net/docs/basics/user-interface/intro...

[1]: https://platform.uno/docs/articles/getting-started/counterap...

[2]: https://learn.microsoft.com/en-us/dotnet/maui/xaml/fundament...

[3]: https://github.com/AvaloniaUI/Avalonia.Markup.Declarative

[4]: https://github.com/fsprojects/Avalonia.FuncUI

I’m curious what you don’t like about Dart? I thought I wouldn’t like it but I’ve found it surprisingly nice.

you mean CSS?

What? No one in the Flutter team got fired. The only ones who potentially had something to do with it were people on the Google Cloud team that ran the pipelines for Flutter builds, but even then, they didn't directly work on Flutter, and their roles just got outsourced anyway to Europe, so it's not like Flutter itself was actually affected.

What the fuck are you talking about? This literally never happened.

The first image at the bottom of that post may be related to your question: https://www.reddit.com/r/rust/comments/191b2to/rinf_copies_a... Btw, why is your name green?

And then there's also crux [1], which is the same "write your mobile app business logic once in Rust", but instead of Flutter, integrates directly with native iOS/Android/Web UIs

[1] https://redbadger.github.io/crux/

Note that the linked thread by OP has now been resolved and the rinf author fixed and apologized [0]. This thread might be a better start on the differences [1].

[0] https://github.com/cunarist/rinf-status-report

[1] https://www.reddit.com/r/FlutterDev/comments/1dnwagk/flutter...

Thank you!

Dart is also safe.

While dart is definitely not like rust, dart is a very safe language. I'd love a dart+rust project if the package ecosystem wasn't such a mess in dart

Not at all, pretty much all popular languages (except C/C++) are as safe as (safe) rust. The only safety rust brings to the table is memory safety, which most languages achieve with a runtime and a garbage collector, which have a performance tradeoff.

> Why not just use the Chrome render engine directly from Rust?

This is what projects like Tauri (in Rust) and Wails (in Go) are doing[0][1]. Utilizing Webview to develop applications, but they still don't support mobile, Tauri mobile is in beta.

Basically Tauri and Wails are on one side (HTML/CSS) trying to approach cross platform by supporting mobile platforms, while Flutter and Kotlin Compose Multiplatform started from the other side.

So it depends on your needs, web-first or mobile-first, and what platforms matter to you. So far Flutter is in the lead offering the most polished experience when it comes to supporting all platforms (Web, desktop, iOS, Android).

[0] https://github.com/tauri-apps/tauri

[1] https://github.com/wailsapp/wails

They used to be based on Skia but now they have their own renderer (Impeller). That said rendering is only a small part of a UI toolkit, there's a ton of other stuff e.g. how to interact with system libraries, integrate with UI paradigms (e.g. tray icons, gestures, responsiveness, widgets).

There's too much infrastructure on top of the render engine to replicate. Flutter is backed by Google and has a fairly large ecosystem of community packages.

See Freya - which uses Skia - the render engine Flutter used until a while back.