🥥 Cocoanut

A minimal, declarative macOS GUI framework for Rust.

Why Cocoanut?

Quick Start

use cocoanut::prelude::*;

fn main() -> cocoanut::Result<()> {
    let count = state(0);
    let inc = count.clone();
    let dec = count.clone();

    app("Counter")
        .size(400.0, 300.0)
        .build()
        .root(
            View::vstack()
                .child(View::text("Counter").bold().font_size(20.0))
                .child(View::label(&format!("Count: {}", count.get())).font_size(32.0))
                .child(View::hstack()
                    .child(View::button("+").on_click_fn(move || inc.increment()))
                    .child(View::button("-").on_click_fn(move || dec.decrement()))
                )
        )
        .run()
}

What's New in v0.3.0

Direct Closures

No more manual event ID management:

// Before (v0.2.0)
event::register(1, || count.set(count.get() + 1));
View::button("+").on_click(1)

// After (v0.3.0)
View::button("+").on_click_fn(|| count.increment())

State Helpers

let count = state(0);
count.increment();  // +1
count.decrement();  // -1
count.reset();      // → 0

let text = state(String::new());
text.append("hello");
text.clear();

let flag = state(false);
flag.toggle();

Styling DSL

use cocoanut::prelude::*;

let btn_style = style()
    .width(100.0)
    .height(40.0)
    .padding(10.0)
    .background(color("blue"))
    .foreground("white")
    .corner_radius(8.0);

View::button("Click Me").styled(&btn_style)

Component Macros

component! {
    header,
    View::hstack()
        .child(View::text("My App").bold())
        .child(View::spacer())
        .child(View::button("Settings"))
}

stateful_component! {
    Counter {
        count: State<i64>,
        label: String,
    } => |this| {
        View::vstack()
            .child(View::text(&this.label))
            .child(View::button("+").on_click_fn(move || this.count.increment()))
    }
}

Async Support

View::button("Fetch Data")
    .on_click_async(|| async {
        let data = fetch_from_api().await;
        state.set(data);
    })

CLI Tool

# Install
cd cli && cargo install --path .

# Create new project
cocoanut new myapp
cd myapp && cargo run

# Development
cocoanut run --watch    # Hot reload
cocoanut build --release

Architecture

12 source files. ~4000 lines. 32 view types. Extensive unit 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
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
component.rs     → Component macros
style.rs         → CSS-like styling DSL
async_support.rs → Async/await support

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
• Direct Closures — on_click_fn(|| ...) without manual IDs
• Event System — event::register(id, closure) + ObjC target/action dispatch
• Dark Mode — .dark() / .light() / set_appearance() at runtime
• Accessibility — .accessibility("label") on any view
• Style Modifiers — .width(), .bold(), .background(), .on_click()
• CSS-like Styling — style().width(100).padding(10).background("blue")
• 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 + new API
cargo run --example native_features  # native Cocoa integration

Developing

cargo test — full library tests (AppKit stubs only under cfg(test)). cargo build --workspace includes the optional CLI crate.

License

Apache-2.0