[plt-scheme] Current trunk of web server apparently broken

From: Matthew Flatt (mflatt at cs.utah.edu)
Date: Sat Apr 28 21:32:22 EDT 2007

At Sat, 28 Apr 2007 21:11:33 -0400, "Jay McCarthy" wrote:
> I know about this error and I've been waiting for the maintainer of
> the unit system to tell me what it means and how to fix it. 

There's been a breakdown in communication, then --- maybe I lost track
of something. I didn't realize that there was an open question.

> > Servlet exception:
> > compound-unit: unit argument expects an untagged import with signature
> > servlet^, which this usage context does not supply

The error means that, in some `compound-unit' form and for one of its
link clauses, the unit expression produces a unit that expects a
`servlet^' import, and the link clause doesn't provide it.

One difference between the old unit system and the new one is that
defined signatures have a specific run-time identity; two signatures
are not equivalent even if they have exactly the same content. Saying
"with signature servlet^", then, is arguably misleading, because there
could be lots of signatures named `servlet^' in different modules and
in different namespaces.

Knowing a bit about the way the web server works, my guess is that the
servlet is loaded in a namespace with a diferent instance of the
`servlet^' signature than the named at the `compound-unit' expression.


Posted on the users mailing list.