user.clj

(ns user
  (:require [schema.core :as s]
            [schema.utils :as s-utils]))

(defn filter-walker
  "Creates a walker which replaces sub-trees in values of maps with nil
  if they do not conform to schema."
  [schema]
  (s/start-walker
   (fn [schema]
     (let [walk (s/walker schema)]
       (fn [x]
         (let [result (walk x)]
           (if (and (s-utils/error? result) (map? x))
             nil
             result)))))
   schema))
   
(def deep-filter
  (filter-walker [{:foo {:bar (s/enum 42)
                         s/Any s/Any}
                   s/Any s/Any}]))

(clojure.pprint/pprint
 (deep-filter
  [{:foo {:bar 32}}
   {:foo {:bar 42 :baz 1}}]))

;; [{:foo nil} {:foo {:baz 1, :bar 42}}]