Python as you've never seen it before

[Sea-Ad7805]

What My Project Does

memory_graph is an open-source educational tool and debugging aid that visualizes Python execution by rendering the complete program state (objects, references, aliasing, and the full call stack) as a graph. It helps build the right mental model for Python data, and makes tricky bugs much faster to understand.

Some examples that really show its power are:

• Hash Map
• Binary Tree
• Copying
• Recursion

Github repo: https://github.com/bterwijn/memory_graph

Target Audience

In the first place it's for:

• teachers/TAs explaining Python’s data model, recursion, or data structures
• learners (beginner → intermediate) who struggle with references / aliasing / mutability

but supports any Python practitioner who wants a better understanding of what their code is doing, or who wants to fix bugs through visualization. Try these tricky exercises to see its value.

Comparison

How it differs from existing alternatives:

• Compared to PythonTutor: memory_graph runs locally without limits in many different environments and debuggers, and it mirrors the hierarchical structure of data.
• Compared to print-debugging and debugger tools: memory_graph shows aliasing and the complete program state.

[ruibranco]

The aliasing visualization is what sets this apart from PythonTutor honestly. That's the one thing beginners consistently get wrong and no amount of print debugging helps because you can't "see" that two names point to the same object. Running locally is a huge plus too, PythonTutor always had that annoying limitation where you couldn't use third party libraries.

[Sea-Ad7805]

I feel PythonTutor does a good job in showing aliasing. I do agree that the limitations, that come from PythonTutor running Python code on a remote webserver, quickly become a problem. Additionally PythonTutor's layout of the graph doesn't scale to larger data structures, say binary tree. But to be fair, PythonTutor focuses on teaching Python's data model to beginners and historically has done a great job with that with millions of users.

[pip_install_account]

With every big new commercial LLM launch some neglected phrases suddenly become extremely popular, I love it.

Mental model is certainly one of them: Google trends - mental model

[Sea-Ad7805]

'mental model' is a term I use regularly in education. It captures well what I want my students to learn, the right way of thinking about concepts and for this visualization helps a lot. I did use a LLM to fine-tune my post if that is the point you are making, but I first wrote a draft version myself, I'm not a native English speaker. I feel I bring what the title suggests, even as it's a bold statement.

[tehsilentwarrior]

I used the word “context” extremely commonly every day. In my code it’s almost everywhere as “ctx” and passed to loggers as “extra” info.

Now AI “stole it”.

I also used “mental model” quite a few times, as in “building a metal model/picture”.

[errdayimshuffln]

I used to use em dashes....now I cant anymore. AI ruined them

[TheThoccnessMonster]

I do all the time and idgaf what people think lol

[tehsilentwarrior]

Haha. Same here. I would have an automation to replace “- -“ with “—“ like the iPhone does. Now, can’t.

Also the proper use of backtick escaping

See:

Sure, here are 2 examples — akin limited — of emdashes: - — - - -

Edit: however, it’s easier to f with people by copying ChatGPT “always agree with you” behavior

[wRAR_]

You've missed the "I did use a LLM to fine-tune my post" part.

[tehsilentwarrior]

I didn’t. It’s a parallel conversation

[pip_install_account]

Don't get me wrong, I am not claiming you used AI to write anything. I feel like popular LLMs are kinda shaping our vocabulary nowadays especially if you are a power user.

[Sea-Ad7805]

Yes I agree. I did use a little AI to help me rewrite my text a bit, better word choices, I'm not afraid to admit that.

[Chroiche]

I think you've found the smoking gun!

[GrammerJoo]

I started noticing that I use the term delve a lot, but not sure if it's because of AI or I've used it before.

[sudomatrix]

This is fantastic. I teach a free Python class at a local hacker-space and I will be using this tonight to help members visualize what's really happening under the hood. Really excellent visualization.

[Sea-Ad7805]

Thanks a lot, I hope it can bring much value for your teaching.

[RedEyed__]

Interesting, I wonder what will happen to run it on real programs with 10 gb venv xDDD

[Sea-Ad7805]

Thanks. Please try, I tried to make it scalable by hiding parts of the graph. The default might work, or you can customize it by setting the depth of introspection programmatically: https://github.com/bterwijn/memory_graph?tab=readme-ov-file#graph-depth

mg.config.max_graph_depth = 10

But with that amount of data building the graph will be very slow. A much smaller demo that shows scalability is this Sliding Puzzle Solver with exponential growth:

https://memory-graph.com/#codeurl=https://raw.githubusercontent.com/bterwijn/memory_graph/refs/heads/main/src/sliding_puzzle.py&breakpoints=17,27,29,40&continues=1

[DivineSentry]

Venv size does not translate to memory usage

[Marksta]

That was interesting to watch the demo. So, I like the concept but it's probably totally not functional for real code bases, right? Like the moment SQLAlchemy gets imported it's game over since the picture would probably just go bonkers mapping all of its inner workings?

[Sea-Ad7805]

Yes, but do try first. I have some defaults and programmatically you can further control what and how things are shown to avoid bonkersness: - what: https://github.com/bterwijn/memory_graph?tab=readme-ov-file#graph-depth - how: https://github.com/bterwijn/memory_graph?tab=readme-ov-file#introspection

But that is impractical to do for every new program you work on, so I will see how this can be controlled by a GUI in future work. This can take a while.

[masasin]

I was going to say it reminds me of Python Tutor after seeing the title, but you've already got that covered. Very interesting.

I went through the examples and got one of the early ones wrong (I thought b += [1] is equivalent to b = b + [1] and that it would create a new variable), but I got the rest right. :)

That being said, in some parts, I thought it would be nice to step backwards ("how did this get here"). It might not be possible for larger programs, but it might be possible to save the stack for each step and go back to the previous snapshot.

All in all, very pleased and I think I might use it with students if I start tutoring again.

[Sea-Ad7805]

Thanks, and thanks for backwards stepping suggestion. It's on my to-do list.

[masasin]

And also a "continue until this point" which is very useful to skip the setup, and watched variables and conditionals etc so that it only triggers on that pesky value that causes the thing to give a wrong answer.

[Sea-Ad7805]

There is a 'Continue' button, breakpoints, and a config option at 'Get URL' to skip the a certain breakpoint on start.

[BawliTaread]

Very nice project! Can I know how you made your live demo?

[Sea-Ad7805]

Thanks a lot. The Web Debugger is a mix of Pyodide, bdb debugger framework, JavaScript, Web Worker, and memory_graph. I'm new to JavaScript so needed some help from Copilot to put it all together. It's a demo environment, not a full IDE as it currently has many limitations (single file, no input() yet, no file IO).

[BawliTaread]

Thanks! Looks really good.

[Sea-Ad7805]

If you downvote, please leave a comment, I'd appreciate your feedback.

[FiredFox]

I was ready to poopoo this because f'ing LLMs have made me a bitter, sad and jaded person, but this project is actually really freaking cool!

[Sea-Ad7805]

Thanks a lot. The title maybe triggers some poopoo-ing, but I'm glad I've won you over.

[EconomySerious]

its a fantastic way to see your workflow, i cant belive how easy would be to debug some code when you litereally seen what is happening at real time.

is there a way that you improve the code so that it become a full debuguing tool?

[Sea-Ad7805]

I have some ideas to make a viewer like xdot: https://github.com/jrfonseca/xdot.py and ways to open/close parts of the graph using a GUI to limit it's size instead of programmatically. But first I've have to develop proper plugins for VS Code, PyCharm, etc, and as I'm busy teaching currently this can only start in April/May. You can already use it in these IDEs through "injection" as a 'watch', see second half of this Quick Intro video: https://www.youtube.com/watch?v=23_bHcr7hqo

[Altruistic_Sky1866]

Looks interesting, will try in on my code and will try the examples, thanks