Yup, I had gleaned that much from context. My issue is taht I don't know what a functor is! Sure, I could look it up, but my problem is that I spend all my ti

Yup, I had gleaned that much from context. My issue is taht I don't know what a functor is! Sure, I could look it up, but my problem is that I spend all my time looking things up. At some point, this gets in the way of proper understanding. It's a strong signal that I'm missing some foundational knowledge. (Your reply is most appreciated, though!)