JSON was used in the original article as a placeholder for Clojure forms. You can (optionally) get strong typing using Clojure records[1] (see defrecord) or using core.typed[2]. Datomic also lets you specify types[3].
I'm not "coming back" to you, as I don't appreciate your snarky, know-it-all tone. I'm replying for the benefit of others reading who may not be familiar with Clojure.
I think the parent is saying basically:
Greenspun's eleventh rule
Any sufficiently complex Lisp implementation contains
an ad hoc, informally-specified, bug-ridden, slow
implementation of half of Haskell's type system.