Initial prototype: hack recursive functions to look themselves up in the function's pre-bound consts, instead of doing a global namespace lookup

x.py

import dis


def filter_code(func, replacement):
    name = func.__name__
    code = func.__code__.co_code
    begin, do_fix = None, None
    for i in dis.get_instructions(func):
         if begin is not None: # every time except the first
             end = i.offset
             yield replacement if do_fix else code[begin:end]
         begin, do_fix = i.offset, (i.opname == 'LOAD_GLOBAL' and i.argval == name)
    # handle the last
    yield replacement if do_fix else code[begin:]


def rewrite(func):
    consts = func.__code__.co_consts + (func,)
    load_opcode = bytes([dis.opmap['LOAD_CONST'], len(consts) - 1])
    fixed_code = b''.join(filter_code(func, load_opcode))
    func.__code__ = func.__code__.replace(co_consts=consts, co_code=fixed_code)
    return func # for decorator usage