the-ns

(the-ns x)

clojure.core/the-ns: the namespace x names -- a symbol naming one the program created (with ns or in-ns, above the call), one it required, or clojure.core -- or x itself when it is a namespace. Any other symbol signals No namespace: x found, like the oracle. A namespace prints as #object[clojure.lang.Namespace "name"] and str answers its name. As a value a one-argument function.

user true true
No namespace: no-such found