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Comment by mkw5053 | Hacker News Reader

I went through her book "Category Theory in Context" a few years ago and loved it! It's a great introduction to the field.

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Thanks for the tip! Looks like she put the PDF of the book up here: https://math.jhu.edu/~eriehl/context.pdf

From the same page:

> The Mathemagician’s Axiom of Textbook Prerequisites: Let M be the minimum actual prerequisites for an average student being able to read and understand a given presentation of a subject in a mathematics textbook. Let A be the author’s stated prerequisites. Then usually: A <<<<<<< M

> ... My intended audience might be described as peri-graduate students, ranging from advanced mathematics undergraduates, to graduate students, to perhaps even research mathematicians in other disciplines.

So, you're saying a well-read Ph.D. in abstract math is the pre-requisite for reading that book?

Regardless of your level, just remember to set your pacing expectations. It's perfectly okay if you are going slow, it's really information-dense.

I have no background in abstract math. It took me three days to make it through the first paragraph. I'd still recommend it.

I think the prerequisite for "Category Theory in Context" is a grasp of basic category theory ((co-)limits, Yoneda lemma, adjoint functor theorems, etc). You should also have some interest in an abstract maths field that requires all these category theory machinery. So a graduate student in abstract maths sounds about right.

I went through it with some background abstract algebra and functional programming

Thanks for the link. I ordered the print book five minutes ago and it will be good to have the PDF also.

I have used Haskell for years, but consider myself a novice at dealing with Monads, etc., while good at writing pure Haskell code. (I wrote a Haskell book, which is free on my website https://markwatson.com/books/).

A few years ago, I randomly had dinner with a math professor who specialized in Category Theory, and it was a very cool conversation. I hope that reading Emily Riehl’s book and listening to some of her teaching videos, that I can grok enough CT to enjoy it.

I've been trying to buy markwatson.com for years!!!

I think it's fairly misleading to think of impure computation as a core part of the `Monad` abstraction in Haskell[0]. Most of the places I use monads in Haskell are pure e.g. error handling, parsers, working with DSLs. `IO` is where the impurity lives and the monad abstraction just makes it a bit more fun to use, but it isn't essential to the impurity. Haskell had IO before it had monads. I also feel like the emphasis on the Monad abstraction really sells Functor and Applicative short as they are fantastic abstractions in their own right in addition to being important building blocks for the Monad abstraction.

[0] https://news.ycombinator.com/item?id=20112333

https://www.reddit.com/r/haskell/comments/eoo16m/base_catego...

Thanks for the link and clarification.

Also A Survey of Categorical Concepts: https://math.jhu.edu/~eriehl/survey.pdf

Thanks. I was just about to ask. I'm merely a double bassist, but maybe I can at least grasp a bit of it. ;-)

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