Scieneer Common Lisp 1.3.9 online documentation

merge-pathnames pathname &optional defaults default-version[Function]

Construct a new pathname from pathname filled in unspecified components from the defaults and default-version. The created pathname will have the same class as the given pathname - irrespective of the pathname host. For the pathname directory, name and type components the customary case of the defaults is mapped to the customary case for the pathname.