This is very well done. It's refreshing to see graphical explanations of programming concepts. The analogy with tracks is a very helpful way to make the notion

This is very well done. It's refreshing to see graphical explanations of programming concepts. The analogy with tracks is a very helpful way to make the notion of monadic contexts concrete. Great job! I'd be curious to know how the author came up with the idea of representing these ideas with tracks, as it is a very fortunate perspective.