Great use of the same example under three different dependency injection mechanisms.

One issue I see with the Reader pattern, however, is that anyone using one of these injected methods has to deal with the monad stuff of using for comprehensions to extract the values, et cetera, whereas with the other two patterns they get to use normal functions.

Put another way: having to distinguish between the "normal" functions in a class versus the injected Reader functions, and not be able to use them in the same way, feels like it would get old fast. I wonder if the author has found this annoying or not.

I do really like how purely functional the Reader approach is though, no state!