# Category Theory for Programmers by Bartosz Milewski

Hacker Approved page: https://hackerapproved.com/p/category-theory-for-programmers/

5 people recommended Category Theory for Programmers by Bartosz Milewski in Hacker News comments and none criticized it, November 2025 to October 2026. It was recommended in 2 of 12 months, in 3 threads. It does not meet the Hacker Approved badge rule.

3 of the 5 people who recommend it commented in one thread, “Actegories”.

**Verdict:** Recommended as an approachable intro to category theory aimed at programmers, available as a free blog series and YouTube lecture series.

Summary written by Claude from 5 comments.

## Why people recommend it

- Approachable introduction to category theory (2 comments in the sample): "an intro to and overview of category theory aimed at programmers" ([source](https://news.ycombinator.com/item?id=48906348)) "it came across as an approachable intro to the math" ([source](https://news.ycombinator.com/item?id=48179225))
- Written specifically for programmers (1 comment in the sample): "a blog series on CT specifically for programmers" ([source](https://news.ycombinator.com/item?id=48783905))

## Other online courses people recommend

- [Nand2Tetris](https://hackerapproved.com/p/nand2tetris/): 26 recommend, 2 mixed, 3 criticize
- [Math Academy](https://hackerapproved.com/p/math-academy/): 25 recommend, 8 mixed, 1 criticize
- [Neural Networks: Zero to Hero by Andrej Karpathy](https://hackerapproved.com/p/neural-networks-zero-to-hero/): 25 recommend, 2 mixed, 1 criticize
- [CS336: Language Modeling from Scratch](https://hackerapproved.com/p/cs336-language-modeling-from-scratch/): 11 recommend, 1 mixed, 0 criticize

## The badge

A product earns the Hacker Approved badge when at least 10 people recommend it, recommenders outnumber critics at least 2 to 1 (mixed feelings count toward neither side), it was recommended in at least 4 of the 12 months and in at least 5 different threads, and no single thread supplies more than half of the people who recommend it. Health and money products are never badged.

## Cite as

Hacker Approved, "Category Theory for Programmers by Bartosz Milewski", https://hackerapproved.com/p/category-theory-for-programmers/ (5 recommend, 0 mixed, 0 criticize; Hacker News comments, November 2025 to October 2026).

Counts updated 3 Nov 2026, with data through October 31, 2026.