Failed sexpr finder

gistfile1.txt

(ns parser
  (:require [clojure.tools.reader :as reader]
            [clojure.tools.reader.reader-types :as rt]
            [clojure.zip :as zip]))


(defn try-read [rdr]
  (when rdr
    (reader/read rdr false ::EOF)))

(defn lined-read [string]
  (let [rdr (rt/indexing-push-back-reader string)]
    (take-while #(not= ::EOF %) (repeatedly #(try-read rdr)))))

(defn in-form? [{:keys [line column end-line end-column]} pos]
  (and (some #{(:line pos)} (range line (inc end-line)))
       (some #{(:ch pos)} (range (inc column) end-column))))

(defn code->zip [code-str]
  (-> code-str lined-read zip/seq-zip))

(defn find-sexpr [cur pos]
  (cond
   (zip/end? cur) nil
   (not (list? (zip/node cur))) (find-sexpr (zip/next cur) pos)
   :else  (if (in-form? (meta (zip/node cur)) pos)            
            (if-let [child (find-sexpr (zip/next cur) pos)]
              child
              {:form-str (pr-str (zip/node cur))
               :meta (meta (zip/node cur))})
              (find-sexpr (zip/next cur) pos))))


(def sample "
(defn jalla 
  \"Jalla functions rules\"
  [a b]
  (let [dill (str a b)] ; yeah this makes a lot of sense right ?
    (println (str \"jalla\" dill))))

; What on earth
(def a 4)")

(find-sexpr (code->zip sample) {:line 6 :ch 24}) ; ok

; DOH ! returns the let .. 
; because zip/seq-zip well expect nested sequences, so vectors become a leaf node... 
(find-sexpr (code->zip sample) {:line 5 :ch 16})