Haskell also has only one namespace. I propose that Clojure took it from there, including persistent data structures, lazy data structures, ...

> But loop/recur sure looks to be ultimately inspired by Scheme style use of TCO;

To me it looks more like ancient Lisp with prog and goto.

    (defun foo ()
      (prog ((a 1))
        start
        (print a)
        (when (< a 10)
          (incf a)
          (go start))))

Old Lisp code is full of that. It's basically what LOOP/RECUR provides.