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  6. Langchain

LangChain

LangChain is the most popular framework for building AI applications powered by large language models (LLMs).

LangChain publishes multiple Python packages. The following are provided by the Workers runtime:

​​ Get Started

Clone the cloudflare/python-workers-examples repository and run the LangChain example:

git clone https://github.com/cloudflare/python-workers-examples
cd 04-langchain
npx wrangler@latest dev

​​ Example code

index.py
from js import Response
from langchain_core.prompts import PromptTemplate
from langchain_openai import OpenAI


async def on_fetch(request, env):
  prompt = PromptTemplate.from_template("Complete the following sentence: I am a {profession} and ")
  llm = OpenAI(api_key=env.API_KEY)
  chain = prompt | llm


  res = await chain.ainvoke({"profession": "electrician"})
  return Response.new(res.split(".")[0].strip())