mirror of
https://github.com/hwchase17/langchain
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138 lines
10 KiB
Markdown
138 lines
10 KiB
Markdown
# 🦜️🔗 LangChain
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⚡ Build context-aware reasoning applications ⚡
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[](https://github.com/langchain-ai/langchain/releases)
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[](https://github.com/langchain-ai/langchain/actions/workflows/check_diffs.yml)
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[](https://opensource.org/licenses/MIT)
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[](https://pypistats.org/packages/langchain-core)
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[](https://star-history.com/#langchain-ai/langchain)
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[](https://libraries.io/github/langchain-ai/langchain)
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[](https://github.com/langchain-ai/langchain/issues)
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[](https://vscode.dev/redirect?url=vscode://ms-vscode-remote.remote-containers/cloneInVolume?url=https://github.com/langchain-ai/langchain)
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[](https://codespaces.new/langchain-ai/langchain)
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[](https://discord.gg/6adMQxSpJS)
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[](https://twitter.com/langchainai)
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Looking for the JS/TS library? Check out [LangChain.js](https://github.com/langchain-ai/langchainjs).
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To help you ship LangChain apps to production faster, check out [LangSmith](https://smith.langchain.com).
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[LangSmith](https://smith.langchain.com) is a unified developer platform for building, testing, and monitoring LLM applications.
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Fill out [this form](https://www.langchain.com/contact-sales) to speak with our sales team.
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## Quick Install
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With pip:
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```bash
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pip install langchain
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```
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With conda:
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```bash
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conda install langchain -c conda-forge
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```
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## 🤔 What is LangChain?
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**LangChain** is a framework for developing applications powered by large language models (LLMs).
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For these applications, LangChain simplifies the entire application lifecycle:
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- **Open-source libraries**: Build your applications using LangChain's open-source [building blocks](https://python.langchain.com/v0.2/docs/concepts#langchain-expression-language-lcel), [components](https://python.langchain.com/v0.2/docs/concepts), and [third-party integrations](https://python.langchain.com/v0.2/docs/integrations/platforms/).
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Use [LangGraph](/docs/concepts/#langgraph) to build stateful agents with first-class streaming and human-in-the-loop support.
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- **Productionization**: Inspect, monitor, and evaluate your apps with [LangSmith](https://docs.smith.langchain.com/) so that you can constantly optimize and deploy with confidence.
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- **Deployment**: Turn your LangGraph applications into production-ready APIs and Assistants with [LangGraph Cloud](https://langchain-ai.github.io/langgraph/cloud/).
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### Open-source libraries
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- **`langchain-core`**: Base abstractions and LangChain Expression Language.
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- **`langchain-community`**: Third party integrations.
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- Some integrations have been further split into **partner packages** that only rely on **`langchain-core`**. Examples include **`langchain_openai`** and **`langchain_anthropic`**.
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- **`langchain`**: Chains, agents, and retrieval strategies that make up an application's cognitive architecture.
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- **[`LangGraph`](https://langchain-ai.github.io/langgraph/)**: A library for building robust and stateful multi-actor applications with LLMs by modeling steps as edges and nodes in a graph. Integrates smoothly with LangChain, but can be used without it.
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### Productionization:
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- **[LangSmith](https://docs.smith.langchain.com/)**: A developer platform that lets you debug, test, evaluate, and monitor chains built on any LLM framework and seamlessly integrates with LangChain.
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### Deployment:
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- **[LangGraph Cloud](https://langchain-ai.github.io/langgraph/cloud/)**: Turn your LangGraph applications into production-ready APIs and Assistants.
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## 🧱 What can you build with LangChain?
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**❓ Question answering with RAG**
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- [Documentation](https://python.langchain.com/v0.2/docs/tutorials/rag/)
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- End-to-end Example: [Chat LangChain](https://chat.langchain.com) and [repo](https://github.com/langchain-ai/chat-langchain)
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**🧱 Extracting structured output**
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- [Documentation](https://python.langchain.com/v0.2/docs/tutorials/extraction/)
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- End-to-end Example: [SQL Llama2 Template](https://github.com/langchain-ai/langchain-extract/)
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**🤖 Chatbots**
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- [Documentation](https://python.langchain.com/v0.2/docs/tutorials/chatbot/)
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- End-to-end Example: [Web LangChain (web researcher chatbot)](https://weblangchain.vercel.app) and [repo](https://github.com/langchain-ai/weblangchain)
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And much more! Head to the [Tutorials](https://python.langchain.com/v0.2/docs/tutorials/) section of the docs for more.
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## 🚀 How does LangChain help?
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The main value props of the LangChain libraries are:
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1. **Components**: composable building blocks, tools and integrations for working with language models. Components are modular and easy-to-use, whether you are using the rest of the LangChain framework or not
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2. **Off-the-shelf chains**: built-in assemblages of components for accomplishing higher-level tasks
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Off-the-shelf chains make it easy to get started. Components make it easy to customize existing chains and build new ones.
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## LangChain Expression Language (LCEL)
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LCEL is the foundation of many of LangChain's components, and is a declarative way to compose chains. LCEL was designed from day 1 to support putting prototypes in production, with no code changes, from the simplest “prompt + LLM” chain to the most complex chains.
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- **[Overview](https://python.langchain.com/v0.2/docs/concepts/#langchain-expression-language-lcel)**: LCEL and its benefits
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- **[Interface](https://python.langchain.com/v0.2/docs/concepts/#runnable-interface)**: The standard Runnable interface for LCEL objects
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- **[Primitives](https://python.langchain.com/v0.2/docs/how_to/#langchain-expression-language-lcel)**: More on the primitives LCEL includes
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- **[Cheatsheet](https://python.langchain.com/v0.2/docs/how_to/lcel_cheatsheet/)**: Quick overview of the most common usage patterns
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## Components
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Components fall into the following **modules**:
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**📃 Model I/O**
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This includes [prompt management](https://python.langchain.com/v0.2/docs/concepts/#prompt-templates), [prompt optimization](https://python.langchain.com/v0.2/docs/concepts/#example-selectors), a generic interface for [chat models](https://python.langchain.com/v0.2/docs/concepts/#chat-models) and [LLMs](https://python.langchain.com/v0.2/docs/concepts/#llms), and common utilities for working with [model outputs](https://python.langchain.com/v0.2/docs/concepts/#output-parsers).
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**📚 Retrieval**
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Retrieval Augmented Generation involves [loading data](https://python.langchain.com/v0.2/docs/concepts/#document-loaders) from a variety of sources, [preparing it](https://python.langchain.com/v0.2/docs/concepts/#text-splitters), then [searching over (a.k.a. retrieving from)](https://python.langchain.com/v0.2/docs/concepts/#retrievers) it for use in the generation step.
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**🤖 Agents**
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Agents allow an LLM autonomy over how a task is accomplished. Agents make decisions about which Actions to take, then take that Action, observe the result, and repeat until the task is complete. LangChain provides a [standard interface for agents](https://python.langchain.com/v0.2/docs/concepts/#agents), along with [LangGraph](https://github.com/langchain-ai/langgraph) for building custom agents.
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## 📖 Documentation
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Please see [here](https://python.langchain.com) for full documentation, which includes:
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- [Introduction](https://python.langchain.com/v0.2/docs/introduction/): Overview of the framework and the structure of the docs.
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- [Tutorials](https://python.langchain.com/docs/use_cases/): If you're looking to build something specific or are more of a hands-on learner, check out our tutorials. This is the best place to get started.
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- [How-to guides](https://python.langchain.com/v0.2/docs/how_to/): Answers to “How do I….?” type questions. These guides are goal-oriented and concrete; they're meant to help you complete a specific task.
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- [Conceptual guide](https://python.langchain.com/v0.2/docs/concepts/): Conceptual explanations of the key parts of the framework.
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- [API Reference](https://api.python.langchain.com): Thorough documentation of every class and method.
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## 🌐 Ecosystem
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- [🦜🛠️ LangSmith](https://docs.smith.langchain.com/): Trace and evaluate your language model applications and intelligent agents to help you move from prototype to production.
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- [🦜🕸️ LangGraph](https://langchain-ai.github.io/langgraph/): Create stateful, multi-actor applications with LLMs. Integrates smoothly with LangChain, but can be used without it.
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- [🦜🏓 LangServe](https://python.langchain.com/docs/langserve): Deploy LangChain runnables and chains as REST APIs.
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## 💁 Contributing
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As an open-source project in a rapidly developing field, we are extremely open to contributions, whether it be in the form of a new feature, improved infrastructure, or better documentation.
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For detailed information on how to contribute, see [here](https://python.langchain.com/v0.2/docs/contributing/).
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## 🌟 Contributors
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[](https://github.com/langchain-ai/langchain/graphs/contributors)
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