Programming with Categories
Brendan Fong, Bartosz Milewski, and David Spivak, have just kicked off a new course at MIT called Programming with Categories. I don't live in Boston so I can't attend the course, but I am watching the videos as they come out. In lecture 2 (about time 5:30), Brendan introduces the informal concept of Shape.
I very much like this idea of shapes, where each Shape suggests "the essence of" a basic idea in Category Theory. To me this provides a way to informally use these concepts. I can take this essence and use it in any way that provides some practical value.
This is roughly the table that Brendan presented.