Installation and Verification

Install LangChain, langchain-core, and langchain-text-splitters.

python3 -m pip install langchain langchain-core langchain-text-splitters

After the installation is complete, record the actual version.

python3 -m pip show langchain langchain-core langchain-text-splitters

Check whether LangChain is successfully installed.

Create the verification script validate_langchain_basic.py.

import langchain
import langchain_core
from langchain_core.prompts import ChatPromptTemplate
from langchain_core.runnables import RunnableLambda
from langchain_text_splitters import RecursiveCharacterTextSplitter

def validate_imports():
    print("langchain=" + langchain.__version__)
    print("langchain_core=" + langchain_core.__version__)

def validate_runnable():
    runnable = RunnableLambda(lambda value: value + 1)
    result = runnable.invoke(1)
    assert result == 2
    print("runnable_result=" + str(result))

def validate_prompt():
    prompt = ChatPromptTemplate.from_template("Hello, {name}!")
    messages = prompt.format_messages(name="ARM")
    assert len(messages) == 1
    assert "ARM" in messages[0].content
    print("prompt_result=" + messages[0].content)

def validate_text_splitter():
    splitter = RecursiveCharacterTextSplitter(chunk_size=20, chunk_overlap=5)
    chunks = splitter.split_text("LangChain runs successfully on ARM platform.")
    assert len(chunks) > 0
    print("chunk_count=" + str(len(chunks)))

if __name__ == "__main__":
    validate_imports()
    validate_runnable()
    validate_prompt()
    validate_text_splitter()
    print("LangChain basic validation passed")

Perform the verification.
1
python3 validate_langchain_basic.py

The following is the expected output.

langchain=
langchain_core=
runnable_result=2
prompt_result=Hello, ARM!
chunk_count=
LangChain basic validation passed

Acceptance Criteria

The basic compatibility verification is passed if the following items are met.

**Table 1** Acceptance criteria
Item	Check Criteria
Installation	LangChain, langchain-core, and langchain-text-splitters can be installed using pip.
Import	No exception occurs when importing langchain and langchain_core.
Runnable	RunnableLambda can be executed properly and return the expected result.
Prompt	ChatPromptTemplate can format messages properly.
Text splitter	RecursiveCharacterTextSplitter can split text properly.

FAQs

If the installation fails, check whether the Python version meets the dependency requirements.

python3 --version
python3 -m pip index versions langchain
python3 -m pip index versions langchain-core

If a message is displayed indicating that the wheel fails to be built, record the complete error log and pay attention to the following information:

**Table 2** Information Description
Information	Description
Python version not meeting requirements	You need to replace the Python version with one that meets the dependency requirements.
Build tool missing	You may need to install build dependencies such as GCC and python3-devel.
No Arm wheel	The dependency package may not provide the wheel for the current platform. You need to build the wheel using the source code.

The basic verification should not proactively introduce dependencies such as vector databases, document parsing, embedding, and external model calling. If these dependencies report errors, handle them separately as extended verification issues.

Parent topic: Installation Guide