Rosanswers logo

I have what seems to be a completely standard ROSLisp configuration. I have the talker and listener tutorials working; in fact so does the add-two-ints-server, but the add-two-ints-client script triggers an error in SBCL:

The symbol "ADD-TWO-INTS-CLIENT-MAIN" is not external in the ROSLISP-TUTORIALS-BASICS package.

The script looks fine:

(ros-load:load-system "roslisp_tutorials_basics" "roslisp-tutorials-basics")

So I´m guessing that there is a manipulation of the package environment somewhere deep in the ROS libraries that may not work on every system. These guys on the Web discovered a pretty subtle bug that caused similar behavior. They said:


You are destructively changing the package-nicknames list of PACK. Don't do that.

Changing this to:

(defvar *built-in-packages*
  (mapcan (lambda (pack)
            (cons (package-name pack) 
                  (copy-list (package-nicknames pack))))

makes the problem go away.

Is it possible that having quicklisp installed would conflict with ROS? I´m at SBCL 1.3.1. Is it advised to upgrade?


Originally posted by toddcpierce on ROS Answers with karma: 51 on 2016-09-02

Post score: 0

Original comments

Comment by gvdhoorn on 2016-09-03:\

These guys on the Web

'these guys'?

Comment by gvdhoorn on 2016-09-03:
Looking at the responses to other Lisp related questions, I have the feeling that the ROSLisp community isn't very large (any more). It might take some time before you get a reply.

It would be very nice if you could report back on any solution/work-around you find. That would help immensely.

Comment by gaya on 2016-09-07:
Could you please point at the particular part of the roslisp tutorial from the ROS wiki page when this error happens? I suspect that you are not following the tutorial.

The problem that you encountered is a minor issue, I doubt greatly that it is connected to an SBCL bug.

Comment by toddcpierce on 2016-09-07:
I did another pull of the add-two-ints tutorial and it worked. By the way, I was not implying that there was a bug in SBCL. It´s just that I´m really putting the configuration of Lisp through a lot while doing other experiments. You saved me again. How do I close this?

Comment by gvdhoorn on 2016-09-07:
You could accept the answer by @gaya by ticking the checkmark to the left of the answer. That would mark the question as answered.

Comment by gvdhoorn on 2016-09-07:
We don't typically close questions here on ROS Answers. Marking the question as answered is much more visible from the question list.


1 Answer 1


Rosanswers logo

I committed a fix to the tutorial. Do a git pull and try again. I strongly recommend, though, that you follow the text in the tutorials on the ROS wiki page, e.g. here:


The text in those tutorials will help a lot to figure out what is going on in the tutorial code.

Originally posted by gaya with karma: 311 on 2016-09-07

This answer was ACCEPTED on the original site

Post score: 1


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.