Found 4 comments on HN
semigroupoid · 2017-03-11 · Original thread
I second the recommendation for Artin's Algebra. I'd also recommend Paolo Aluffi's Algebra: Chapter 0, which is a nice alternative to Lang and also uses category theory right from the beginning and doesn't require many prerequisites.

[0] https://www.amazon.com/Algebra-Chapter-Graduate-Studies-Math...

SchemeLisp · 2015-07-30 · Original thread
Slightly off-topic here, but flipping through this[1] Abstract Algebra textbook(2009), I found it amusing that the author thanks NSA for support among others :D.

[1] http://www.amazon.com/Algebra-Chapter-Graduate-Studies-Mathe...

j2kun · 2015-02-24 · Original thread
The best exposition I've found for demystifying category theory is the first few chapters of Paolo Aluffi's Algebra: Chapter 0 [1]. The central emphasis is on universal properties, which I see most treatments for beginners de-emphasize or ignore (as these slides do). From my experience, universal properties are the main tool for unifying and abstracting concepts into the language of categories. Aluffi uses category theory to unify the treatment of groups, rings, modules, linear algebra, and then goes on to more abstract category theory. I have also written a bit on this [2], regrettably choosing ML as the language of implementation.

[1]: http://www.amazon.com/Algebra-Chapter-Graduate-Studies-Mathe...

[2]: http://jeremykun.com/2013/04/24/introducing-categories/

Digging deeper into the HN thread that you linked to, I came across this discussion [1] on Reddit which is focused more on the abstract algebra question. They recommend Algebra: Chapter 0 by Aluffi (Amazon [2] or PDF [3]).

[1] http://www.reddit.com/r/math/comments/1eiyid/category_theory...

[2] http://www.amazon.com/Algebra-Chapter-Graduate-Studies-Mathe...

[3] http://www.mimuw.edu.pl/~jarekw/pdf/Algebra0TextboookAluffi....

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