Introduction to Actegories in Category Theory

Bartosz Milewski published a new blog entry on June 30, 2026 titled **“actegories.”** The post appears on his personal site and explores a concept that blends ideas from category theory with functional programming, offering a fresh perspective on how actions can be organized within mathematical structures. Milewski’s writing typically delves into the theoretical underpinnings of programming languages, and this article continues that tradition by proposing a new framework that he calls “actegories.”

The entry was shared on Hacker News, where it received seven up‑votes and no comments. While the post did not spark discussion on the platform, its modest reception suggests that it reached a niche audience of readers familiar with category theory and functional programming. Milewski’s work is frequently cited in academic and industry circles, and “actegories” adds to his body of thought‑provoking material on the intersection of mathematics and software design.