cl-darcs can access repositories on a local disk (read and write) and on an HTTP server (read-only). Unlike the original darcs client, it doesn't yet support access through SSH; you can emulate that with scp or rsync.
When passing a path of a local repository to cl-darcs, it should usually
be a directory pathname, not a file pathname. That is, add a trailing
slash, as in "/path/to/repo/", not "/path/to/repo". Most
functions can handle both forms (using
CL-FAD:PATHNAME-AS-DIRECTORY), though.
If you want to use a proxy for HTTP access, set this variable to e.g. "proxy.example.com:3128". When NIL, no proxy is used.
Using a caching proxy (e.g. Squid) can be a good idea, since cl-darcs is sometimes a bit wasteful about how much it downloads, and bugs might make it lose what it already has downloaded.