So, I finished Computer Science study about 3 years ago (I'm 28 now) and lately I've been craving math.
But I've started to realize most of the latest work I did was just bringin/glueing some premade components/services together. And this is not as fun. I remember programming being about problem solving. Hard problems we had to solve in college were really fun. So I started to learn a bit of Haskell.
Haskell is a pure functional programming language that has alot of constructs from category theory. Constructs like functors, monoids, monads and so on. Learning a bit about this was fun again. Then I started looking into category theory, and altough I did understand the basics I was missing some other fundemantls. So I started backtracking to see what I would have to learn to be able to understand it and then I realized, that maybe this side of programming is what I want to do. More on the theoretical/math side.
I really want to learn more math (and of course relearn what I don't remember anymore from college) so I would be able to use it well with my programming knowledge. Category theory is just one of many things I'd like to know.
So here goes the question...
How hard would it be to learn math on my own from sources like Khan Academy and online videos lectures from universities like MIT, Harvard and books and so on. Or should I consider pursuing another degree in mathematics? I don't have problems with time since I work when I want (no fixed hours).