@amszmidt @screwtape I thought you'd like the example.
It was one of the first things I learned (and definitely not the easiest way to learn!). I don't use it very often, but when I need it, it is so much nicer to look at. It just confuses the hell out of people who don't understand, or ignore the List part of LISp.
Using CnnnnR accessors is awesome when coding something like a Sudoku solver, where you have to consider rows, blocks and columns.