I would like to read the function name on the stack element i. How can I read the name?It looks like you're confusing the C API's stack with the interpreter's runtime stack. They're different animals :)The stack exposed in the C API is basically just a mechanism for passing arguments to C functions -- that's the stack you're interacting with when you call lua_iscfunction. In the context of the C-API's stack, functions don't have names. They're just pointers.