The Importance of Understanding the Different Abstraction Mechanisms

I always think that it's very difficult to explain monads in Haskell and what they give you as an abstraction mechanism if you haven't first suffered from the fact of not having them available. And it's the same with O as well. I mean, there are some good ideas in object during the programming but if you start with them, it's not clear what bad ideas they're replacing. But at the same time, then like to contrast this, I always think like when I had my first course on functional programming - we spent a month talking about fold are. It was sort of the culmination of the whole chorus to talk about for now that we've seen all these different functions on lists