gistfile1.txt

(defn smap [state func coll]
  (loop [state state
         ans '()
         coll coll]
    (if (empty? coll)
      (reverse ans)
      (let [[ns v] (func state (first coll))]
        (recur ns
               (cons v ans)
               (rest coll))))))

(defn smap
  "Given a function of [state in-val -> [state out-val]], an initial
  state, and a collection of input values, yield the output values as
  the function is walked over the inputs with state kept up to date."
  [f state xs]
  (when (seq xs)
    (let [[new-state out] (f state (first xs))]
      (cons out (lazy-seq (smap f new-state (next xs)))))))

=> (smap (fn [s i] [(inc s) (+ s i)]) 0 [10 100 1000 10000])
(10 101 1002 10003)