objc:objectp

(objc:objectp value)

Whether the value is an Objective-C object reference (an object or a class). Works on every machine. 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> (objc:objectp (objc:string "x"))
T
CL-USER> (objc:objectp "x")
NIL