Ponder
See what a library function does, one step at a time, right next to your code.
Put your cursor on a call such as np.clip(...) or chunk(...) and press Alt+W. Ponder opens a
short animation that walks through what the function does with example values: shapes move, captions explain each
step, and you go at your own pace.
No setup. No accounts. Nothing to configure.
Where the animations come from
- The library itself. Library authors can ship a
ponder.json with their package. These animations come from
the people who wrote the code, and Ponder always prefers them.
- Your own folders. Put
ponder.json files in a .ponder folder in your project, for example animations you
made or downloaded.
- The community index. For popular libraries that ship no animation yet (NumPy, lodash, date-fns,
more-itertools and more), Ponder can fetch one from the free Ponder Index.
Every example in it is checked against the real library.
Built-in functions too. sorted(...), "a,b".split(","), arr.map(...), Math.max(...), v.push(x),
strings.Split(...): functions of the language itself (Python, JavaScript/TypeScript, Rust, Go) are looked up the
same way.
Never a dead end. When there is no animation, Ponder tells you why and what to try, with buttons for the fixes:
install the missing language extension, trust the folder, install a missing library, pick the Python interpreter,
retry, or update Ponder. How to fix… opens a page with every step.
Your privacy
- Ponder asks once before it ever goes online: Allow, Not now or Never.
- Only the package name is requested, for example
pypi/numpy. Never your code, your file names or your
function names.
- Your own code is never looked up anywhere.
- Downloaded animations are kept on your computer, so they also work offline.
Controls
| Key |
Action |
| Alt+W |
open Ponder for the call at the cursor |
| → / ← |
next / previous step |
| Space |
play / pause |
| A |
play all steps automatically |
| R |
replay |
| Esc |
close |
Ponder follows your light or dark theme and your system's reduced-motion setting.
Languages
Works in any language whose VS Code extension supports Go to Definition: Python, JavaScript and TypeScript out of
the box, Java with the Java extension, and Rust, Go, C/C++, PHP, Ruby and more with their usual extensions.
Something not working?
- "Restricted Mode": VS Code turns language support off in folders you have not trusted. Click
Trust Folder… when Ponder asks.
- No animation for a function: nobody has written one yet. Library authors can add one in an afternoon, see
below.
- Details of every lookup: View → Output → Ponder.
Settings
All optional: ponder.onlineLookup (ask / on / off), ponder.localFolders, ponder.autoplay,
ponder.reducedMotion. Command palette: Ponder: Clear Cached Animations.
For library authors
Add an animation for your own functions: a ponder.json next to your package.json (or pyproject.toml,
Cargo.toml, ...). Right-click one of your functions and choose Copy Ponder Symbol to get its exact name, then
see the guide.
License
MIT
