Hi, it seems https://clojurescript.org/about/differences#_hinting is not up to date. Clearly, at least ^string hinting has some benefit in various places as I learned from @mfikes What is the current state of type hinting in ClojureScript?
in short, I'd say this is not documented, but you can go a far way seeing where the (private!) analyzer API is used in order to infer the types of some values and emit different JS code depending on the inferred type
for a concrete example of this: check out the macro definition of cljs.core/str