mtm

(def ^{:dynamic true} *print-progress* true)

(defmacro with-progress
  "Bind a `reportfn` function, and evaluate `body` wherein
  calling (report!) will invoke the report function with the current
  state of the iteration."
  [reportfn & body]
  `(let [iter# (atom 0)
         reporter# ~reportfn]
     (letfn [(~'report! []