LangChain Expression Language - The ONLY video you need to TRULY understand LCEL

In this video, we'll do a deep dive into the LangChain Expression Language—the backbone of LangChain. This is the only video you'll need to really understand the ins and outs of LCEL and its Runnable Interface.

Timestamps:

0:00 - Intro
0:37 - Basic Chain and invoke method
3:06 - The magic of the pipe operator
8:11 - RunnablePassThrough
9:02 - RunnableLambda
10:03 - RunnableParallel
13:00 - More complicated chains
18:35 - Real world Chain - easy!

#langchain #LCEL

[riteshsingh]

I am working in Deloitte as consultant and your videos helped me to train other folks. Love from India ❤

[pratiknarendraraut]

Best teacher on YouTube, get this man on million subs asap.

[eloiseidlitz]

Purely helpful ! I love it ! Big thank to you !

[efneogearbox]

This is one of the best LCEL tutorials, not directly copying examples from LangChain website. Thank you!

[ramishelh]

One of the best tutorials on LCEL. Thanks a lot!

[Songobu]

very nice tutorial! thank you very much! appreciate your work very much

[matuskokoska]

exctremely helpful video, thank you very much <3

[deadlooop]

Gave you the the * in git repo, and subscribed as well 👍

[sjtpmgv]

It's awesome video!!! I finally figured out how it works! Thank you very much! ❤❤❤❤

And I absolutely agree with idea that this great video should be in their shitty docs

[yazanrisheh]

This definitely helped me understand more about LCEL. Thank you so much.

Just to make sure I understood what you explained in the video, runnablepassthrough is simply taking any input variable and it keeps it as it is to pass it to another runnable right? For example if I wanted to implement memory in my RAG application, I would create a function and where the input of it is from the runnablepassthrough and I pass that into a runnablelambda. If I had another function, I'd do the same and pass it inside runnablelamdba and finally to construct the entire chain, I connect them all to a runnable parralel. Is this right?

Also, sometimes I see "itemgetter" on langchain docs. Could you explain what that is

[pnhbs]

around 19 min, `{"context": retriever | format _docs, "question": RunnablePassthrough ()}` is the first item in the chain ... how exactly does that get coerced to a RunnableParallel? What does the coercing and when is it done? In Python, `__or__` is called on the item to the left of the operator, which here is a dictionary ...

[farhanafridi]

Is their any way i can include memory in the code you provided at the last?

I am encountering errors while doing it.

[Kubex]

How would it work if I had more than one input var in the prompt. For example, my prompt has {height} and {weight} how do I pass both values with runnable ?

[nintendo]

what vs code extension are you using to run notebooks?

[Lowlightu]

Amazing video!
Interestingly the result of the RAG was Tuna instead of "thuna", any idea why it didn't use the word from your documents and supposedly used its own knowledge.

[jacehua]

Really great video so I'm guessing you can actually pass the metadata the same way that you do at the end so the LLM can consider the metadata as well?

[abhinavmane]

Hey I am building a bot for a call centre but I want the bot to do a credential check first like confirm the name how do I achieve that please respond.

[dkdmdbt]

Can you share the notebook? It'd be of great help!

[ericmagalhaes]

If possible I would give 1k likes! that solved hours of studying!

[kacperwodarczyk]

in their shitty documentation should be a links to your videos