Acknowledgments

This book has been writing itself for about twenty-five years. Don't be fooled by its current form---I merely polish and adorn what has been taking shape all along. Every part of this book has a history of collaboration. Every idea is a recombination of what surrounds us. Behind these words are people.

Those with whom I shared thinking and teaching at the university. The most influential on me: Nicolás Passerini, whom I also worked with in industry for many years, and whom I consider a brother and Jedi master. But also Carlos Lombardi, Fernando Dodino, Hernán Liendo, Juan Pablo Picasso, my brother Guillermo Fernandes, and many others.

People from whom I learned in industry, with whom we had fun building excellent madness: Nicolás Barrera, Federico Lochbaum (with whom I also shared teaching, his masterful Wing Chun classes, and a great friendship), Martín Vergara, and Kevin Bruner.

Several examples in this book---distributed state management, undo/redo, branching history---are based on the system we built at Beanie with Nico Barrera, Fede Lochbaum, Martín Vergara, and Kevin Bruner (one of the founders of Telltale Games). A product providing tools and a runtime for conversational games and "choose your own adventure" experiences.

With Nicolás Passerini, Carlos Lombardi, Pablo Tesone, Leo Gassman, and Fernando Dodino, we spent many years exploring object-oriented programming. Together with many others, we built Wollok---a language to support a pedagogical path for teaching OOP, with multiple visualization modes and a game programming environment. From this emerged questions of linguistics: we constructed a language whose elements had precisely the semantics needed for the previously discovered pedagogical journey---no more, no less.

Also with Nico Passerini, we built an architecture for a large project with its own ORM and web framework. On top of that ORM, a system of transparent object-based transactions---like an aspect.

And finally, to you, the reader. You carry this book forward into places I cannot imagine.

---J.F. Buenos Aires, Argentina, 2026