Actegories | Hacker News Reader

Actegories

bartoszmilewski.com

51 pointsibobev9 comments

If you saw TFA and thought "hmmm yes, I know some of those words", then I can recommend the author's own lecture series on YouTube [0]. It's an intro to and overview of category theory aimed at programmers, with the requisite context and motivation for why anyone should care. It's long but worth the time investment IMHO.

0: http://www.youtube.com/playlist?list=PLbgaMIhjbmEnaH_LTkxLI7...

He also has an excellent online/PDF version of the material[0]. All of it is really mind opening stuff, and fun!

[0] https://bartoszmilewski.com/2014/10/28/category-theory-for-p...

this has a real "a monad is a monoid in the category of endofunctors" energy to it

> To understand actegories, let’s start with the definition of a monoidal category

Definitely not written for someone with my starting knowledge, haha.

I'd like to understand how and why this stuff is useful for programmers.

Watch his lecture series on YouTube. We you started programming, you had to adapt your brain to the way of thinking of computer programs. Think of this as an continuation of that evolution, were you acquire new methods of reasoning that can abstract many apparently different problems into the same concept.

Is it only applicable in e.g. Haskell, though, or is it language agnostic? Thanks for your answer.

In a different comment thread, someone mentioned the book, Category Theory for Programmers. Here's the Releases page with PDF files (click to open the Assets section). https://github.com/hmemcpy/milewski-ctfp-pdf/releases

There are several versions with code examples in Haskell, OCaml, ReasonML, and Scala. These are all typically associated with functional programming and category theory. However, category theory is a much wider and deeper subject than any specific language, and deals with mathematical objects and concepts relevant to (more or less) all of programming.

Uh thanks but I'm gonna stick with Scattergories for now.

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