Author here. It's fun to see this post 14 years later! If you like this, you might also enjoy: - Prolog: This is an entire language built around choice and ba

Author here. It's fun to see this post 14 years later! If you like this, you might also enjoy: - Prolog: This is an entire language built around choice and backtracking. https://en.wikipedia.org/wiki/Prolog https://en.wikipedia.org/wiki/Prolog - The Reasoned Schemer, which builds a Prolog-in-Scheme from first principles. This book is excellent, or even mind-blowing if you're never seen this before. https://mitpress.mit.edu/books/reasoned-schemer https://mitpress.mit.edu/books/reasoned-schemer - Oz/Mozart: This language takes the basic idea even further, adding concurrency and constraint solving. There's an older book about this that's nice: https://www.info.ucl.ac.be/~pvr/book.html https://www.info.ucl.ac.be/~pvr/book.html It feels like Oz was an evolutionary dead end, but an interesting one. - Probability monads. You can extend this general idea to include probability distributions over values. I have an older series of blog posts at http://www.randomhacks.net/probability-monads/ http://www.randomhacks.net/probability-monads/ that explains this idea piece-by-piece, but there's been a ton of research in the past decade on probabilistic languages: http://www.probabilistic-programming.org/wiki/Home http://www.probabilistic-programming.org/wiki/Home It's definitely a fun topic!