Crux enables cross-platform application development by sharing a Rust-based business logic core across mobile (iOS/Android) and web targets. It targets developers seeking to maximize code reuse for application behavior while leveraging native or declarative UI frameworks like SwiftUI, Jetpack Compose, or React/Vue. This approach aims to reduce development time and improve consistency by centralizing complex logic in a single, testable Rust codebase.

How It Works

Crux employs an architecture inspired by Elm, strictly separating pure computational logic from side effects. The Rust core is compiled into platform-specific libraries (static library for iOS, dynamic library via JNI for Android, WebAssembly for web). Side effects, such as API calls or time-based operations, are managed by the core as explicit Effect requests, which are then executed by the platform-specific "Shell." This isolation makes the core side-effect-free, enabling fast, high-level user journey tests without needing mocks or stubs. Communication between the core and shell is message-based, with type generation ensuring static type checking across languages for events, models, and effects.

Quick Start & Requirements

• Install/Run: Follow the "Getting Started" guide for project setup.
• Prerequisites: Rust toolchain, platform-specific SDKs (iOS, Android, Web).
• Resources: Project setup involves compiling Rust code and integrating with platform UI projects.
• Links: Introductory Talk, Book, API Docs, Zulip Community

Highlighted Details

• Managed Effects: Side effects are captured as values, allowing for portable and testable core logic.
• Type Generation: Static type checking across Rust, Swift, Kotlin, and TypeScript for core interfaces.
• Elm Architecture: Utilizes Event, Model, Effect, and ViewModel components with an update function for state management.
• WebAssembly Target: Core logic can be compiled to Wasm, ensuring isolation and security.

Maintenance & Community

Crux is actively developed and sponsored by Red Badger Consulting Limited. A Zulip community channel is available for discussion.

Licensing & Compatibility

The project appears to be licensed under the MIT license, allowing for commercial use and integration with closed-source applications.

Limitations & Caveats

Crux is pre-1.0 and under active development, meaning occasional breaking API changes may occur. The Capability API is being deprecated in favor of a new Command API, indicating ongoing architectural evolution.