I’m also not English native speaker. :) Please excuse my poor ability to explain things. I’ve rewrote your code example using stamps about a year ago. Here it is: https://medium.com/@koresar/fun-with-stamps-episode-5-composition-design-pattern-fe55721c571a
Please, do not percept that old article as a personal attack. I just wanted to show that eater and pooper (omg, these names!) can be separate concerns using stamps.
Also, I don’t like the term “concatenative inheritance”. I believe it describes stamps in a very bad manner. Stamps are not concatenative inheritance! The term is highly misleading. :(
It’s probably hard for stamp newbies to get their head around the code I wrote. I just though you probably haven’t seen my article and wonder if you can proof read it?