(how (in 'python (write (interpreter 'lisp))
:-P
(howp (write (interpreter :of :lisp :in :python))))
“how?” is not a predicate (i.e. something that returns a Boolean value), so it wouldn't be named howp.
A minimal version would be more like:
# REPL
def interpret_lisp():
while not control_C_pressed(): print(eval(read()))
:)