clojure - Clojure: What is the easiest way to remove all the nil items in a nested data structure?

Question

Say we have this nested vector:

(def coll [nil [["this" nil "this"] nil] nil "this"])

How would you design a remove-nil function so that all nil disappear?

(remove-nil coll)
;> [[["this" "this"]] "this"]

Answer 1

(clojure.walk/postwalk #(if (coll? %) (into (empty %) (remove nil? %)) %) coll)
;=> [[["this" "this"]] "this"]