Back when I didn't understand what a monad was, I would read a bunch of tutorials and get confused by the analogies and examples. For example, I would get confused by comparisons to "boxes," or I would think that Maybe was the definition of a monad, or that IO was the definition of a monad.
The information in the tutorial that you link seems to be all correct. However, it's too "jumpy" for my tastes. The tutorial talks about "contexts," but doesn't really explain what a "context" is, except for making a comparison to "boxes." I get that a functor is an abstract idea, so explaining it in an understandable way is difficult. However, I wish that the article would discuss type constructors, because the idea of mapping types to types is an important part of the definition of functor. Without this explanation, I imagine that the comparison to "boxes" would have given the past me the wrong impression of what a functor is.
In my tutorial, I sought to teach the actual definition of a functor, applicative, and monad. I explain that a functor maps types to types and functions to functions in a way that preserves composition and identity, that an applicative preserves the product, and that a monad is characterized by a "join" operation that "flattens" the data and a "return" operation that "wraps up" the data. I actually would have preferred to explain the actual category theory, but I felt that it would be too intimidating, and so I attempted to convey the ideas in a non-category-theory way. With my current understanding of functor, applicative, and monad, I believe that if one doesn't learn their actual definitions, one doesn't truly understand them. I guess that I wanted my tutorial to be more rigorous.
However, I am not an expert on teaching, so maybe I'm taking the wrong approach.
See my Reddit comment: https://www.reddit.com/r/programming/comments/cy35zz/functor...