A Crash Course in Category Theory - Bartosz Milewski

Programming is math and math is programming. But the kind of math that's useful in programming is not what they teach you in school. In fact it's much more interesting. Category theory seems to be esoteric when presented by mathematicians, because all their examples come from other branches of mathematics. But when you use examples from programming, things suddenly becomes quite obvious. And the reason there is such a close fit between category theory and programming is quite simple: both are built on the principle of composability.

Compiling like a boss!

[sami-pl]

The most friendly presentation ever which helped me to connect the dots

[nawdawg]

Lol that dude who was like “we got time” is our hero! He’s already helped 20k people.

[Krumpetify]

The last 15 minutes were so over my head, I'm going to need a functor to lift the knowledge into my mind.

[haypierre]

This guy is my heroe in terms of knowledge, vision and kindness. Would love to meet him one day.

[atreeon]

'If you are looking for reasons to study category theory, maybe you should just enjoy it', oh yeah!

[vnshngpnt]

I rewatch it 1 year after initial watch and I think I only now understood Yoneda embedding. That's rather an intense crash course for 1 hour :D I strongly recommend Bartosz Category Theory course on YouTube.

[kahnfatman]

Functor Monad Applicative Expletive... btw, *BIG THANKS* to Dr.Bartosz - thanks to his series on Category Theory that I understand Haskell and the reasoning behind it all.

[cheari]

Wow, Bartosz makes these very complicated ideas easy to understand. Thank you very much.

[cyamdirl]

Samuel Eilenberg (September 30, 1913 – January 30, 1998) was a Polish-American mathematician who co-founded category theory with Saunders Mac Lane.

[notgate]

Great talk! I wish he gave a few more concrete examples in between some of the theories. I'm just going to end up creating examples of how to use the concepts in my head anyway, so I want the examples I come up with to actually be valid. I could be misunderstanding how to actually apply some it (like Yoneda Embedding).

[onomatopoeial]

A practical introduction to Category Theory - Daniela Sfregola video is a primer to this one. he basically refers to this for basics around 21:00

[jackozeehakkjuz]

This is the best video I've watched in the whole month. Thanks.

[shangyintan]

In 26:50, he said an incoming arrow could be seen as a constructor, and then he said empty set has no constructors. But isn't there's an arrow from the empty set pointing toward itself?

[bernardofitzpatrick]

Brilliant lecturer - really clear presentation!

[esquilax]

I've watched a few videos on category theory. I've studied set theory and mathematical logic (a long time ago), I've played around with functional programming in ML and Clojure, and I've played with the Isabelle proof assistant/theorem prover. But I've yet to see the point of CT for day-to-day programming.


Is it supposed to help you think about programming in a new way? Or is it more useful for the design of programming languages, or perhaps for proving things about programs?

[tiborfutotablet]

Including the Haskell examples as well (as a link to gists) would be great.

[tomislavhoman]

I was really expecting it to culminate with the monoid in a category of endofunctors ;)

[SigSelect]

The first 10 minutes should be considered the standard argument for what's wrong with mathematics instruction today - he said it so clearly: math should not be about teaching humans how to imitate machine, but should be the best tool humans have to reason about ideas. In reality, true mathematics is the former, but of course we can forgive any laymen whose public education has convinced them otherwise.

[utof]

very very beginner-friendly, which is rare in the field at the moment. Nice!

[harryfan]

Rising high schooler here. I'm surprised that I can even understand some of this stuff! Nice job explaining everything in a quick and concise manner!