27 points by bntr 3 days ago
Originally built as my master's thesis in 2008, Visual Lambda is a graphical environment where lambda terms are manipulated as draggable 2D structures ("Bubble Notation"), and beta-reduction is smoothly animated.
I recently revived and cleaned up the project and published it as an interactive web version: https://bntre.github.io/visual-lambda/
GitHub repo: https://github.com/bntre/visual-lambda
It also includes a small "Lambda Puzzles" challenge, where you try to extract a hidden free variable (a golden coin) by constructing the right term: https://github.com/bntre/visual-lambda#puzzles
For comparison: factorial(3) visualized in two different notations.
John Tromp's Lambda Diagrams (via 2swap): https://www.youtube.com/watch?v=RcVA8Nj6HEo&t=1346s
Bubble Notation: https://www.youtube.com/watch?v=aRgu8S3Pnb8
Here's another from a long time ago: https://dkeenan.com/Lambda/
2swap has some incredible videos
You can also construct your own puzzles and share them via URL.
Example: https://bntre.github.io/visual-lambda/#workspace=H4sIAAAAAAA...