objc:address

(objc:address object)

The object's address as an integer -- the identity a hash table can key on (two references to one object have one address). Signals for anything but an Objective-C object. Part of the macOS-only objc package -- the interpreter (java -jar, or the rontolisp native binary) and a compiled .class / .jar, never a .wasm; on a machine without the runtime it signals an error. See the macOS GUI guide.

CL-USER> (integerp (objc:address (objc:string "x")))
T