Building ReAct agents with LangChain’s Expression Language
LangChain Expression Language (LCEL) offers a declarative approach to constructing ReAct agents. Instead of manually orchestrating the steps, LCEL allows you to define a processing graph that handles user input, reasoning, action selection, and final response generation. This section demonstrates how to implement a ReAct agent using this powerful framework.
The core idea is to establish a data pipeline that takes a user’s query, uses an LLM to reason through a series of steps, potentially leveraging external tools, and ultimately arrives at an answer. This pipeline can be succinctly expressed using LCEL.
The following is a Python code example demonstrating this process:
from langchain_core.prompts import ChatPromptTemplate from langchain_core.runnables import chain from langchain.agents.format_scratchpad import format_log_to_str from langchain.agents.output_parsers import( ReActSingleInputOutputParser...