// the take
A single-page interactive calculator that visualizes matrix multiplication using the author's own 'waterfall method' mnemonic, aimed at high school/college students struggling to internalize the standard row-by-column procedure. It's also presented as a mid-sized reference app for structuring Cycle.js projects (MVI pattern, xstream, onionify).
The visualization itself is a genuinely useful teaching aid — rotating the second matrix 90° and 'combing' values is a clearer mental model than the textbook algorithm, and the animated UI makes that concrete instead of just described. The codebase is deliberately small and fractally organized (each capitalized directory is a self-contained Cycle.js component with its own model/view/intent split), which is a decent worked example for anyone trying to learn Cycle.js's MVI pattern beyond TodoMVC. TypeScript is used throughout, so the component boundaries are at least type-checked.
Cycle.js and xstream are a dead-end stack at this point — nobody is shipping new projects on them, so the 'learning resource' angle only helps someone already committed to a framework with no community momentum left. No tests anywhere in the tree despite the model layer being split into multiple reducer files, which is exactly the kind of logic you'd want covered. Last push was January 2022, and dependencies like TypeStyle and Immutable.js are themselves stale, so cloning this today means wrestling with old tooling before you get to the interesting part. It's a one-off demo site, not a library or package — there's nothing to actually adopt or depend on, just code to read.
We read the README, the directory tree and a key source file in October 2026. Nobody pays to be listed. How we judge →