Wanderland in marimo

A few weeks ago I wrote about Wanderland, my attempt to bring the Swift Playgrounds feeling into Python notebooks. The goal was pretty simple: code on one side, an immediate little world on the other, and enough delight that a beginner wants to keep poking at it.

Vincent from marimo posted a Short about it, which was a fun full-circle moment because Mo the Mossball started with him in the first place. In the video, he shows the exact thing I hoped would come through: Wanderland is not a separate app pretending to be a notebook. It is a notebook-native playground.

There is Mo, there is code next to him, and there is a button that runs the code so you can watch him move through the world. The small technical detail I really like is that the 3D scene is a custom anywidget, while the controls around it are ordinary marimo UI components. Even the editor is marimo’s own code editor.

That is the connection to the original Wanderland post for me. The interesting part is not just that Python can render a cute 3D puzzle. It is that the notebook can become the whole learning environment: instructions, editable code, UI controls, visual feedback, and the result, all in one reactive document.

Vincent posted another Short about a detail I was especially happy with: dark mode. When marimo switches themes, Wanderland does not just invert a few UI colors. The world itself turns to nighttime.

It is a small touch, but it is exactly the kind of thing that makes a notebook feel less like a form with outputs and more like a place you can build in. For teaching, that matters. The environment should invite curiosity before the first line of code even runs.

Also, subscribe to Vincent’s marimo posts. He has been sharing lovely short demos and longer deep dives of what modern notebooks can do.