[lexi-lambda]

Generic is quite specific to Haskell, so it is probably difficult to explain without a little more understanding of Haskell-like type systems. (Rust has some similar capabilities, so that would help, too.) I wouldn’t worry about it too much, though; it doesn’t contain any particularly deep knowledge about type systems in general.

[PartiallyTyped]

Okay, is there like a book or some other resource besides your awesome blog that you'd recommend for people looking to get into this some more?

[lexi-lambda]

Well, like I said, the subject is extremely broad, so it is difficult to give concrete suggestions without knowing what specifically you’d like to get into. But I can give some potential options.

If you’d like to learn Haskell, I think https://www.cis.upenn.edu/~cis1940/spring13/ is still a pretty nice resource. It is quick and to the point, and it provides some exercises to work through. There are lots of things in the Haskell ecosystem that you could explore if you wanted to after getting a handle on the basics.

If you want to learn about programming languages and type systems, you could read Programming Languages: Application and Interpretation (https://cs.brown.edu/courses/cs173/2012/book/), which has a chapter on type systems. Alternatively, if you want a more thorough treatment of type systems, you could read Types and Programming Languages by Benjamin Pierce. However, both PLAI and TAPL are textbooks, and they are primarily intended to be used as supporting material in a university course with an instructor. I think PLAI is relatively accessible, but TAPL is more likely to be a challenge without some existing background in programming languages.

[PartiallyTyped]

The textbooks are exactly what I needed! Thank you!