Top all-time · #262
Bartosz Milewski
Personal blog · bartoszmilewski.comprogrammingmath
Bartosz Milewski's personal blog at bartoszmilewski.com covers programming and math. Since 2012, 181 different Hacker News readers have linked it 304 times, most often “Category Theory for Programmers (2014)”. It is still writing: the last post was on 2026-09-21, and you can follow it by feed.
Often recommended · 17 of 40 sampled comments recommend it?
Why HN links it
HN readers link Milewski's blog, mainly Category Theory for Programmers, as a learning resource for programmers. Posts on C++ memory ordering and Kleisli categories are cited as explanations.
- Recommended for · 17 comments
- Called excellent, fantastic and a favourite; a very good argument on types; highly recommended to programmers.
Summarised by Claude from a sample of 40 HN comments that link here. Each comment is marked recommending, critical or neutral (citing without judging); how this works.
Category Theory, Haskell, Concurrency, C++
Most-linked posts?
- Category Theory for Programmers (2014)61 people · 71 mentions · first linked 2016-08-07
- Category Theory for Programmers9 people · 9 mentions · first linked 2014-10-28
- Who ordered memory fences on an x86? (2008)5 people · 5 mentions · first linked 2017-03-25
- /5 people · 5 mentions · first linked 2016-05-04
- Functorio5 people · 5 mentions · first linked 2021-04-15
- Category: The essence of composition4 people · 4 mentions · first linked 2016-05-19
- Math is an insurance policy3 people · 5 mentions · first linked 2020-02-24
- /3 people · 4 mentions · first linked 2012-05-26
- /2014/09/22/parametricity-money-for-nothing-and-theorems-for-free/3 people · 4 mentions · first linked 2016-06-15
- Understanding Attention in LLMs3 people · 3 mentions · first linked 2025-03-06
What Hacker News says?
Perhaps Category Theory for Programmers? https://bartoszmilewski.com/2014/10/28/category-theory-for-p... There is also a playlist on Youtube https://www.youtube.com/watch?v=I8LbkfSSR58&list=PLbgaMIhjbm...
Comment linking /2014/10/28/category-theory-for-programmers-the-preface/
on “Ask HN: What are you learning?”Submitted Functorio as a story · 697 points
HN discussionI've been reading through Bartosz Milewski's Category Theory for Programmers, and trying to do all the challenge questions. https://bartoszmilewski.com/2014/10/28/category-theory-for-p...
Comment linking /2014/10/28/category-theory-for-programmers-the-preface/
on “Ask HN: What are you learning?”Submitted Functorio as a story · 304 points
HN discussionI found it fun to read this after reading this other post that made the rounds today about AI automating most programming work and making program optimization irrelevant: https://bartoszmilewski.com/2020/02/24/math-is-your-insuranc...
Comment linking /2020/02/24/math-is-your-insurance-policy/
on “Andreessen-Horowitz craps on “AI” startups from a great height”Submitted Category Theory for Programmers (2014) as a story · 267 points
HN discussionNo, definitely not, and I agree with the other sibling replies. I was more specifically responding to the part that was dismissive of the "so you should too" point. Certainly, we can and do develop newer and simpler ways of understanding previous theories. And teaching the historical sequence of events can help with understanding; I myself experienced that with [1] for modern analysis. However, these understanding-a…
Comment linking /2014/10/28/category-theory-for-programmers-the-preface/
on “Why do many math books have so much detail and so little enlightenment? (2010)”Submitted Edward C++Hands as a story · 251 points
HN discussionit's base on a fantastic book https://bartoszmilewski.com/2014/10/28/category-theory-for-p...
Comment linking /2014/10/28/category-theory-for-programmers-the-preface/
on “Ask HN: How to self-learn math?”Submitted Category Theory for Programmers as a story · 231 points
HN discussionYes, that was what I was going for. For what it's worth, https://bartoszmilewski.com/2015/09/01/the-yoneda-lemma/ does a pretty good job of explaining the Yoneda lemma in a programming context. Look for the section "Yoneda in Haskell". As I also tried to say earlier, in practice I suggest learning programming first, and then using the likes of category theory to organise your understanding.
Comment linking /2015/09/01/the-yoneda-lemma/
on “Mathematics for Programmers [pdf]”Submitted Math is an insurance policy as a story · 213 points
HN discussionUnlike the other comments so far, I have a link that is in my opinion NOT generally useful for most programmers. I figured it is worth a share for the programmer who knows all of the math in this post and wants to learn yet more: https://bartoszmilewski.com/2014/10/28/category-theory-for-p... Other people can debate category theory's utility: I have no expert insight of my own to lend.
Comment linking /2014/10/28/category-theory-for-programmers-the-preface/
on “Mathematics for Programmers [pdf]”Submitted Category Theory and Declarative Programming as a story · 167 points
HN discussionMost guys I follow are either rust or haskell developers. @manishearth - rust - https://manishearth.github.io/ @bitemyapp - writer of haskell: first principles @bartoszmilewski - haskell - https://bartoszmilewski.com/ @jdegoes - writes informative FP blog posts - http://degoes.net/ @aaron_turon - rust - https://aturon.github.io/blog/ @pcwalton - rust @nikomatsakis - rust - http://smallcultfollowing.com/babysteps/ @p…
Comment linking /
on “Ask HN: Which developers do you closely follow?”Submitted C++17: I See a Monad in Your Future as a story · 153 points
HN discussionIf anyone is looking to get into Category Theory as a programmer, I would recommend giving Bartosz Milewski's Category Theory for Programmers a shot[0]. Quite good, and you can read it as a blog post on that site or get the ebook/physical book to leaf through. For a more theoretical/less applied approach that's still relevant to computer science/programming, check out Benjamin Pierce's Basic Category Theory for Comp…
Comment linking /2014/10/28/category-theory-for-programmers-the-preface/
on “Applied Category Theory”Submitted Guitar Decomposed: 5. Mutating the Third as a story · 123 points
HN discussion> the requirement to be able to log from pretty much anywhere can lead to messy code Ah, Milewski's example of insight from the supposedly useless mathematical stuff: https://bartoszmilewski.com/2014/12/23/kleisli-categories/ (and the corresponding lecture video).
Comment linking /2014/12/23/kleisli-categories/
on “Monitoring demystified: A guide for logging, tracing, metrics”Submitted Categories for Programmers: The Yoneda Lemma as a story · 109 points
HN discussionThe application of mathematical type theory ( https://en.wikipedia.org/wiki/System_F ) to popular programming languages goes back to 1998 when Philip Wadler designed generics for Java. Local type inference is now used in Visual Basic, Scala, Rust, probably a lot of other new languages I am missing. Gradual types are coming to Clojure and probably Python and Lua. Erik Meijer did a lot of work on bringing monads and F…
Comment linking /
on “Programming by poking: why MIT stopped teaching SICP”Submitted Who ordered memory fences on an x86? (2008) as a story · 86 points
HN discussionBartosz Milewski's blog is a source of knowledge about Haskell and how to apply that knowledge in C++. https://bartoszmilewski.com/2014/10/28/category-theory-for-p...
Comment linking /2014/10/28/category-theory-for-programmers-the-preface/
on “Go's Tooling Is an Undervalued Technology”Submitted Benign data races considered harmful as a story · 82 points
HN discussionGreat point. The technique of currying method parameters such that the last one is the input to the operation also makes chaining Kleislis[0] quite nice, albeit using a bind operator (such as `>>=`) instead of the Thrush combinator operator (`|>`). 0 - https://bartoszmilewski.com/2014/12/23/kleisli-categories/
Comment linking /2014/12/23/kleisli-categories/
on “Left to Right Programming”Submitted Getting Lazy with C++ as a story · 82 points
HN discussionBartosz Milewski's blog: http://bartoszmilewski.com/
Comment linking /
on “John Carmack's comment on Doom 3's code style”Submitted Homotopy Equivalences as a story · 80 points
HN discussionIt is hard to answer because of exactly what ndriscoll said[0] > It's like trying to argue about the distinction between U(1), the complex numbers with magnitude 1, and the unit circle, and getting upset when the mathematicians say "those are 3 names for the same thing". Or saying that writing C is programming but writing in a functional language like Scala or Haskell (or Lean) is not. As ndriscoll suggests, it is t…
Comment linking /
on “The language brain matters more for programming than the math brain? (2020)”Submitted Category: The Essence of Composition as a story · 73 points
HN discussion
