Slick.   Do you like the -> syntax?  I think it pairs well with mappings.   e.g:

`dir -> _` means map the file `dir` into the location `_` in the resulting debian.  In this case, dir being a dummy directory and `_` being a string.

Also, *maybe* this one should grab a known directory instead of requiring one to be passed in....

Like `sys.props("tmp.dir")`.....