// Subclassable, OBVIOUSLY!
static class Module {
  void go(Lisp entry) throws Exit {}
}

static class Exit extends Exception {}

static class SimpleInterpreter {
  void interpret(S src, Module module) {
    for (S line : toLines(src)) {
      Lisp entry = nlParse(line, false, true);
      if (!entry.is("[]", 0))
        try {
          module.go(entry);
        } catch (Exit e) {
          break;
        }
    }
  }
}