lazy-printing.clj

(defn get-pids-for-day [fut-func f pp]  ; add date rangepp
  "fut-func is apply-query-to-pid, f is p-day-qry, pp partitioned-pids.
   Iterate through each n pids making futures for n pids (batch size)"
  (let [results []] ;vec inside vec to mirror readings/days 
    (for [pid-pool pp]
      (let [fut (fut-func pid-pool f)]      
        (while (not (every? future-done? fut))
          (Thread/sleep 500)
          (prn (str "waiting for current future to finish..." (first pid-pool))))   
         (conj results (apply combine-readings (map #(identity @ %) fut)))))))

;create lazy-seq
(def test-run (get-pids-for-day apply-query-to-pid p-day-qry-mini tinyer-pid-pool))

(spit "t2t.txt" (prn test-run)) ; or 
(spit "t2t.txt" (map #(println %) test-run))