I wanted SwiftUI's declarative style and type safety, but for all platforms. So I built WaterUI - a Rust UI framework that gives you the best of both worlds.

Why another UI framework?

I love SwiftUI's approach - declarative, type-safe, with a modern API. But existing cross-platform solutions all have trade-offs:

• SwiftUI: Apple-only
• Flutter: Ignores native look-and-feel
• React Native: JS runtime, not fully type-safe
• Existing Rust frameworks: Either immediate mode (egui) or missing the reactive programming model I wanted

What makes WaterUI different?

Features:

• True native rendering - Uses SwiftUI on Apple platforms (yes, even visionOS/watchOS/widgets!), and gtk4 on GTK desktop (more platform is coming soon...)
• Vue-like fine-grained reactivity - Allows efficient updates without virtual DOM
• Type-safe from top to bottom - Leverage Rust's type system fully
• Declarative & reactive - Familiar to SwiftUI/React developers
• Cross-platform - Supports multiple backends (gtk4 backend and swiftui backend are ready now)

Code Example

use waterui::prelude::*;

pub fn counter() -> impl View {
    let count = Binding::int(0);
    let doubled = count.map(|n| n * 2);
    
    vstack((
        text!("Count: {count}"),
        text!("Doubled: {doubled}")
            .font_size(20)
            .foreground_color(Color::gray()),
        
        hstack((
            button("Increment")
                .action_with(&count,|count| count.increment(1)),
            button("Reset")
                .action_with(&count,|count| count.set(0))
                .foreground_color(Color::red()),
        ))
        .spacing(10),
    ))
    .padding(20)
    .spacing(15)
}

Current Status

The framework is in alpha but actively developed. Core features working:

• Reactive system
• Basic widgets (text, button, stack layouts, etc.)
• SwiftUI backend
• Event handling
• More widgets & styling options
• Android backends
• Animation system

GitHub: https://github.com/water-rs/waterui

Tutorial book: https://water-rs.github.io/waterui/

API Reference: https://docs.rs/waterui/

I'd love to hear your thoughts! Especially interested in:

• Feedback on the API design
• What widgets/features you'd prioritize
• Experience with Rust-Swift interop if you've done it

This is my first major open source project in Rust, so any feedback on the code structure would also be appreciated!

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