🥥 Cocoanut

A minimal, declarative macOS GUI framework for Rust.

Why Cocoanut?

Quick Start

use cocoanut::prelude::*;

fn main() -> cocoanut::Result<()> {
    let count = counter_state(1, 2, 3);
    #[cfg(not(feature = "test-mock"))]
    cocoanut::state::bind_label(&count, 100, |v| format!("Count: {}", v));

    app("Counter")
        .size(400.0, 300.0)
        .build()
        .root(
            View::vstack()
                .child(View::text("Counter").bold().font_size(20.0))
                .child(View::label("Count: 0").font_size(32.0).tag(100))
                .child(View::hstack()
                    .child(View::button("+1").on_click(1))
                    .child(View::button("-1").on_click(2))
                    .child(View::button("Reset").on_click(3))
                )
        )
        .run()
}

Architecture

10 source files. ~3500 lines. 32 view types. 29 tests. Type-safe APIs.

view.rs      → View + ViewKind enum (the ONE core type)
renderer.rs  → View tree → AppKit NSViews (single pass)
app.rs       → App lifecycle + Appearance (dark mode)
event.rs     → Callback registry + ObjC action handler
state.rs     → Reactive State<T> + bind_label
menu.rs      → Menu bar with action dispatch
layout.rs    → Auto Layout support (NSLayoutConstraint)
native.rs    → Native view properties & utilities
delegate.rs  → Delegate patterns for native controls
error.rs     → Error types

32 View Types

• Layout: VStack, HStack, ZStack, Spacer
• Text: Text, Label
• Controls: Button, TextField, SecureField, Checkbox, Radio, Slider, Toggle, Dropdown
• Extended: TextArea, DatePicker, ColorPicker
• Containers: ScrollView, TabView, SplitView, GroupBox, WebView, TableView
• Data: ProgressBar, Image
• Native Controls: SegmentedControl, ComboBox, SearchField, Stepper, LevelIndicator, PathControl
• Extensible: Custom

Features

Core Features

• Reactive State — State<T> with on_change listeners
• Event System — event::register(id, closure) + ObjC target/action dispatch
• Dark Mode — .dark() / .light() / set_appearance() at runtime
• Accessibility — .accessibility("label") on any view
• Menu Actions — MenuItem::on_action(id) wires to callbacks
• Style Modifiers — .width(), .bold(), .background(), .on_click()
• JSON Serializable — ViewDesc for debugging/bridging

Native Cocoa Integration

• Auto Layout — NSLayoutConstraint support with type-safe API
• Native Properties — Direct access to shadows, layers, corner radius, opacity
• Responder Chain — First responder management and key view navigation
• Delegate Patterns — TableView data sources, TextField delegates
• Animation Support — Native AppKit animations
• Pasteboard — Clipboard operations (copy/paste)
• Window Management — Window level, alpha, background color

See NATIVE_COCOA_IMPROVEMENTS.md for detailed documentation.

Examples

cargo run --example minimal_app      # basic view tree
cargo run --example counter_app      # reactive state + dark mode
cargo run --example ui_showcase      # all view types
cargo run --example native_features  # native Cocoa integration

License

Apache-2.0