Thanks for those comments, @didibus.
I keep thinking about The Little Schemer (née The Little Lisper). There are Clojurifications of it on the web. It’s a weird book. There are quirky questions on the left, and answers on the right, and you are supposed to cover up the right side while you think about the left side. You don’t even need a computer, although it’s nice to experiment at a REPL, too. I don’t think most programmers would be willing to work through it in the way that it was intended, and maybe they don’t need to do so. However, when I was a fairly inexperienced programmer, but had been studying Common Lisp on and off for a while, working through The Little Lisper was what, for the first time, allowed me to grok recursion.
The book would not be enough to properly learn Clojure, even rewritten in Clojure. I wonder, though, whether some sort of style like that could help people overcome the initial hump to Clojure programming for most people, if they were willing to sit through the process. The Little Schemer style is so slow, and so simple and friendly, that I have the feeling that it could overcome any countervailing tendencies, if the reader were patient. I don’t know.