Marimo

Here’s a full deep dive into Marimo Python Notebooks—what they are, how they work, use cases, and how they differ from traditional tools like JupyterLab.
Author

Benedict Thekkel

🧠 What Is Marimo?

Marimo is an open‑source, reactive Python notebook system that reimagines how notebooks should operate:

  • Stored as pure .py files (not JSON .ipynb)
  • Reactive runtime: changes to code or UI trigger automatic updates to dependent cells
  • Designed for interactive data work with built-in UI widgets, SQL support, and AI tooling (marimo.io, cfp.scipy.org, docs.marimo.io)

⚡ Reaction Architecture

  • Dependency-driven execution: When you run a cell or interact with a widget, Marimo runs downstream cells—or marks them stale if you’re in lazy mode (docs.marimo.io)
  • No hidden state: deleting a cell deletes its variables from memory (docs.marimo.io)
  • Execution order is topologically sorted based on variable definitions and references, not cell order on the page (docs.marimo.io)

🛠️ Key Features

Feature Description
File format .py (fully git-friendly, diffable, mergeable) (GitHub)
Interactivity Use UI widgets like sliders, dropdowns, data tables—no callbacks needed (docs.marimo.io, GitHub)
SQL-first Native SQL cells for querying DuckDB, Postgres, CSVs, dataframes, etc. (PyPI, GitHub)
AI-native Integrated AI assistant and optional GitHub Copilot support for code suggestions and LLM generation (marimo.io, docs.marimo.io)
Reproducibility Built-in sandboxing and package management; notebooks execute deterministically (Real Python, pretalx.northbaypython.org)
Deployment Serve read-only or interactive notebooks as web apps or export to HTML/WASM via CLI (docs.marimo.io, marimo.io)

⚙️ Getting Started (Quickstart)

pip install marimo
marimo tutorial intro

Then create a new notebook with:

marimo edit my_notebook.py

This launches an editor in your browser—cells are editable and reactive—no extra server needed (marimo.io, marimo.io).

You can also deploy it via:

  • marimo run notebook.py (serves as read-only app)
  • Export to WASM or static HTML
  • Run/test as a normal Python script (GitHub, docs.marimo.io)

🧩 Example Snapshot

import marimo as mo

slider = mo.ui.slider(label="x", min=0, max=10, value=2)
mo.display(mo.md(f"Slider value: **{slider.value}**"))

@mo.react
def square():
    return slider.value ** 2
  • Adjust slider → square() runs automatically
  • mo.md(...), mo.ui.slider(...) generate reactive widgets and output (docs.marimo.io)

👥 Who Uses Marimo?

  • Data scientists, analysts, AI engineers
  • Educators & students—used at places like Stanford—its interactivity suits teaching math, linear algebra, ML easily (marimo.io, marimo.io)

🔄 Marimo vs. JupyterLab Summary

Aspect Marimo JupyterLab
Format .py – plain text, git‑friendly .ipynb – JSON, hard to diff
Execution Reactive DAG-based updates, no hidden state Imperative: manual reruns often necessary
Widgets/UI Native UI with no callbacks required Uses ipywidgets with manual wiring
Deployment CLI-based web apps, WASM exports, script execution Requires external tools (Voila, nbconvert, Streamlit)
Reproducibility Deterministic, sandboxed, version-controlled Prone to hidden state bugs, dependency drift

🚀 Advanced Use & Deployment

  • Generate AI-powered notebooks with marimo new "task description"—prompts can produce full notebooks using LLMs (PyPI, marimo.io, GitHub, docs.marimo.io, docs.marimo.io)
  • Use molab—a free hosted cloud service to create, run, and share marimo notebooks like Google Colab, complete with RAM and package support (marimo.io)
  • Deploy via Docker or behind ASGI servers for production or educational environments (GitHub)

✅ Final Takeaway

Marimo is a modern alternative to JupyterLab, optimized for reproducibility, reactivity, version control, and deployability. It brings the best of notebooks, web apps, and scripting into one cohesive Python-native environment.

Would you like:

  • A side-by-side working example in Marimo?
  • A notebook shared via molab to explore?
  • Tutorials for SQL workflows or AI-powered notebooks?

I’m happy to get you started!

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