Comment by twism

Doesn't stray that much from clojure, so I think it's a lisp thing. To keep bindings in clojure with different length names more readable, people tend to indent like this:

    (let [really-long-name l
          score            (get-score x)
          position         (get-pos) x)
          test             test]
         (...
                ....)))))

Sort of the same effect in the arc snippet in OP.