I am not yet sure whether it's a third mistake to think that it's particularly relevant to understand monads (and friends) outside of a language with (a) the higher-kinded types necessary to actually use them, and (b) a type system that is inconsistent in the face of effects without monads.

I waver between a belief that developers with curiosity about computer science topics will, over time, be quantitatively better developers, and the notion that these are niche topics with limited relevancy.

After all, it's very clear that the Java standard library design committee understands what monads are and where they're useful, since the library is littered with the things, but there's vast numbers of developers out there making effective use of futures, collections, optionals, and streams, building their own intuitions about what "flatMap" means you can get away with, all without reading any monad tutorials.

> The number two mistake people make is being aware of the number one mistake so they go write yet another Monad tutorial in Javascript (or Java or whatever...). Which is why there are so many damn Monad tutorials, all saying pretty much the same thing.

I was lucky seeing this before hitting submit button. Phew that was close.