loro/README.md

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Loro<br/>
Sync state easily with CRDTs
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> **Notice**: The current API and encoding schema of Loro are experimental and subject to change. It is not recommended for use in production environments at this time.

Loro is a CRDTs(Conflict-free Replicated Data Types) library that allows you to persist and sync state easily. It is designed for building [local-first software][local-first]. 

**What are CRDTs**? Conflict-free Replicated Data Types (CRDTs) are data structures that enable automatic conflict resolution. It allows users to make changes together, in real-time or asynchronously, without conflicting and without relying on a central server. 

# Features

## Supported CRDT Algorithms

- **Basic Data Structures**: Includes support for `List` for ordered collections, LWW(Last Write Win) `Map` for key-value pairs, `Tree` for hierarchical data, and `Text` for rich text manipulation, enabling a wide variety of applications.
- **Text Editing with Fugue**: Loro integrate [Fugue](https://arxiv.org/abs/2305.00583), a sophisticated CRDT algorithm designed to minimize conflicts in text editing, which is particularly useful for collaborative document editing.
- **Rich Text with Peritext-like CRDT**: Drawing inspiration from [Peritext](https://www.inkandswitch.com/peritext/), Loro manages rich text CRDTs that excel at merging concurrent rich text style edits, maintaining the original intent of each user's input as much as possible. Details on this will be explored further in an upcoming blog post.
- **Hierarchical Data with Moveable Tree**: For applications requiring directory-like data manipulation, Loro utilizes the algorithm from [*A Highly-Available Move Operation for Replicated Trees*](https://ieeexplore.ieee.org/document/9563274), which simplifies the process of moving and reorganizing hierarchical data structures.

### Features

- **Preserve Editing History**
  - With Loro, you can track changes effortlessly as it records the editing history with low overhead. 
  - This feature is essential for audit trails, undo/redo functionality, and understanding the evolution of your data over time.
- **Time Travel Through History**
  - It allows users to compare and merge manually when needed, although CRDTs typically resolve conflicts well.
- **Shallow Clone**
  - > This feature is work in progress
  - CRDTs suffer from ever-growing doc size and memory use as the document grows. Loro enables you to clone a CRDT that prunes the unwanted history.
  - This work is inspired by [Diamond-types](https://github.com/josephg/diamond-types)

### Features Provided by CRDTs

- **High Performance**
- **Decentralized Synchronization**: Loro allows your app's state can be synced via p2p connections.
- **Automatic Merging**: Say goodbye to merge conflicts. Loro guarantees eventual consistency, automating the merging of concurrent changes.
- **Local Availability**: Data is persistently available on users' devices, ensuring offline functionality and real-time responsiveness.
- **Scalability**: Effortlessly scale your application horizontally thanks to the inherently distributed nature of CRDTs.
- **Delta Updates**: Loro has out-of-the-box support for delta updates.


# Credits

Loro draws inspiration from the innovative work of the following projects and individuals:

- [Ink & Switch](https://inkandswitch.com/): The principles of Local-first Software have greatly influenced this project. The [Peritext](https://www.inkandswitch.com/peritext/) project has also shaped our approach to rich text CRDTs.
- [Diamond-types](https://github.com/josephg/diamond-types): The ingenious OT-like merging algorithm from @josephg has been adapted to reduce the computation and space usage of CRDTs.
- [Automerge](https://github.com/automerge/automerge): Their use of columnar encoding for CRDTs has informed our strategies for efficient data encoding.
- [Yjs](https://github.com/yjs/yjs): We have incorporated a similar algorithm for the effective merging of collaborative editing operations, thanks to their pioneering contributions.
- [Matthew Weidner](https://mattweidner.com/): His work on the [Fugue](https://arxiv.org/abs/2305.00583) algorithm has been invaluable, enhancing our text editing capabilities.

 
[local-first]: https://www.inkandswitch.com/local-first/
[Fugue]: https://arxiv.org/abs/2305.00583
[Peritext]: https://www.inkandswitch.com/peritext/