(ns clojure.examples.hello
(:gen-class))
(defn indexed [coll] (map-indexed vector coll))
(defn index-filter [pred coll]
(when pred
(for [[idx elt] (indexed coll) :when (pred elt)] idx)))
(defn index-of-any [pred coll]
(first (index-filter pred coll)))
(println (index-of-any #{\a \b} "dcbagaahbt"))