Topic

LangChain Expression Language (LCEL) Chains

6 posts on langchain expression language (lcel) chains — part of framework tutorials on the n4n AI blog.

LCEL with n4n.ai: routing between GPT-4o and Llama 3.3

Step-by-step guide to implementing lcel n4n.ai model routing gpt-4o llama with LangChain Expression Language for cost-efficient and resilient LLM inference.

July 19, 20263 min read

Framework tutorialsDefinition

LCEL pipe syntax explained with real examples

LCEL pipe syntax explained: how LangChain's | operator composes runnables into chains, with working Python examples, debugging tips, and fixes for common mistakes.

July 19, 20263 min read

Framework tutorialsGuide

LangChain Expression Language: a beginner's guide

A practical langchain expression language beginner guide: build composable LLM chains with LCEL, avoid common pitfalls, and ship faster.

July 19, 20263 min read

Framework tutorialsHow-to

Composing prompt, model, and parser with LCEL

Learn how to lcel compose prompt model parser into a single runnable LangChain chain with code, deployment notes, and verification steps for engineers.

July 19, 20264 min read

Framework tutorialsHow-to

Building a RAG chain entirely in LCEL

Step-by-step lcel rag chain tutorial: load docs, embed with FAISS, and compose retrieval and generation into one LangChain Expression Language chain. Runnable code included.

July 19, 20264 min read

Framework tutorialsHow-to

Build your first LCEL chain in LangChain

Hands-on tutorial to build first LCEL chain LangChain with runnable Python code: install, prompt, model, parser, stream, fallback, and verify.

July 19, 20263 min read