I'm the author. This is definitely a serious project of mine. I presented about it at the Dyalog '23 User Meeting last October: https://tv.dyalog.com/Dyalo

I'm the author. This is definitely a serious project of mine. I presented about it at the Dyalog '23 User Meeting last October: https://tv.dyalog.com/Dyalog23/?v=bb6sIAJjMeM In a sibling comment, mlochbaum impressively just reads my code without too much effort. However, it is first and foremost written for a domain expert, with all affordances for outsiders discarded in favor of parsimony and direct expression of thought. Even if you know all the APL symbols, you'd need some domain knowledge about parsing and YAML specifically to really understand the why. Learning to read the APL symbols is super easy. Just give yourself a couple weeks of 30 minutes a day or so. That's definitely enough to get you started solving challenge problems. However, "fluently reading APL" is like talking about fluently reading math. The focus is on the concepts and communicating those concepts. Fluency is tied to familiarity with the underlying ideas of the problem domain.