Pipe operator for chain composition in LangChain - Mini Project: Build & Apply

Pipe Operator for Chain Composition in LangChain

📖 Scenario: You are building a simple text processing pipeline using LangChain. You want to chain multiple processing steps together using the pipe operator to create a smooth flow of data transformations.

🎯 Goal: Build a LangChain chain that uses the pipe operator | to compose two simple chains: one that converts text to uppercase, and another that adds an exclamation mark at the end.

📋 What You'll Learn

Create a LangChain chain called uppercase_chain that converts input text to uppercase.

Create a LangChain chain called exclaim_chain that adds an exclamation mark at the end of the input text.

Use the pipe operator | to compose uppercase_chain and exclaim_chain into a new chain called full_chain.

Ensure the final chain full_chain can be called with input text to produce the transformed output.

💡 Why This Matters

🌍 Real World

Chaining small processing steps is common in text processing, chatbots, and data pipelines to keep code modular and readable.

💼 Career

Understanding chain composition with pipe operators helps build scalable and maintainable AI applications using LangChain.

1

Create the initial LangChain chains

Create two LangChain chains: uppercase_chain that converts input text to uppercase using a lambda function, and exclaim_chain that adds an exclamation mark at the end using a lambda function.

LangChain

# Create uppercase_chain and exclaim_chain using LangChain chains
# Your code here

Need a hint?

Use RunnableLambda to create simple chains from lambda functions.

2

Add a configuration variable for input text

Create a variable called input_text and set it to the string 'hello world'.

LangChain

from langchain.runnables import RunnableLambda

uppercase_chain = RunnableLambda(lambda text: text.upper())
exclaim_chain = RunnableLambda(lambda text: text + '!')

# Create input_text variable
# Your code here

Need a hint?

Just assign the string 'hello world' to input_text.

3

Compose chains using the pipe operator

Use the pipe operator | to compose uppercase_chain and exclaim_chain into a new chain called full_chain.

LangChain

from langchain.runnables import RunnableLambda

uppercase_chain = RunnableLambda(lambda text: text.upper())
exclaim_chain = RunnableLambda(lambda text: text + '!')

input_text = 'hello world'

# Compose full_chain using pipe operator
# Your code here

Need a hint?

Use full_chain = uppercase_chain | exclaim_chain to chain them.

4

Complete the chain by calling it with input

Call full_chain with input_text and assign the result to a variable called result.

LangChain

from langchain.runnables import RunnableLambda

uppercase_chain = RunnableLambda(lambda text: text.upper())
exclaim_chain = RunnableLambda(lambda text: text + '!')

input_text = 'hello world'

full_chain = uppercase_chain | exclaim_chain

# Call full_chain with input_text and assign to result
# Your code here

Need a hint?

Call the chain like a function: result = full_chain(input_text).