Clojure: What exactly is tail position for recur?

Question

Whats the precise definition of \"tail position\" for recur in clojure. I would think that it would be the last item in a loop S-expression, but in the example below it seem

Answer 1

Just to supplement the excellent answer from Paul above, The Joy of Clojure (ed1) provides a table (Table 7.1) that shows exactly where tail position is in various forms/expressions, which I've reproduced below. Look for where the word "tail" occurs in each form/expression:

|---------------------+-------------------------------------------+---------------|
| Form                | Tail Position                             | recur target? |
|---------------------+-------------------------------------------+---------------|
| fn, defn            | (fn [args] expressions tail)              | Yes           |
| loop                | (loop [bindings] expressions tail)        | Yes           |
| let, letfn, binding | (let [bindings] expressions tail)         | No            |
| do                  | (do expressions tail)                     | No            |
| if, if-not          | (if test then tail else tail)             | No            |
| when, when-not      | (when test expressions tail)              | No            |
| cond                | (cond test test tail ... :else else tail) | No            |
| or, and             | (or test test ... tail)                   | No            |
| case                | (case const const tail ... default tail)  | No            |
|---------------------+-------------------------------------------+---------------|