alt Hacker NewsThings like atom and symbols are functions in the runtime. A Lisp compiler only has to handle special forms, and function calls. If we see the compiler source code using a special operator that it doesn't handle, either directly using it or via macro expansion, then we know it's not yet self-hosting.
Normally I would assume you were right, but the list of things supported in the compiler includes these items:
List functions: car, cdr
Arithmetic functions: +, -, *, /, mod, 1+, 1-
Arithmetic comparisons: =, <, <=, >, >=, /=
So I think the compiler may not be able to compile calls to arbitrary functions? Maybe I should read the code.