Things built outside work, mostly to find out how something actually behaves rather than how it is described.
A SIMD-optimised dataframe in C++
Columnar dataframe built around explicit vectorisation — the interesting part is the gap between what the compiler will auto-vectorise and what it will not, and how much layout work it takes to close it.
Prediction market machinery in Rust
Pricing and market-making infrastructure for prediction markets. Rust, and the reason I now reach for Rust by default on anything with real concurrency in it.
Server-rendered Rust, one round trip to first paint
Axum and Maud, no client framework. Latin-subset webfont at 10KB and inlined critical CSS put the entire above-fold render inside a single TCP initial congestion window. Written up in the blog.
A linear algebra calculator with variables
Vector and matrix variables, elementary operations, and the less elementary ones — basis calculation, inverses, projection, and least-squares solutions.
Live frequency distribution from the microphone
Reads audio off the system microphone and renders its frequency distribution in real time. A good excuse to actually implement an FFT rather than call one.
Sobel edge detection from scratch
Matrix convolution with a Sobel operator to find regions of high contrast. Image processing with no library doing the interesting part.