Filename Interpretation

The evaluation rules for the Files and Imports clauses do not specify how the sequence of Arcs and Delims making up a DelimPath is converted into a filename in the underlying file system. While this is somewhat system-dependent, it is nevertheless intended to be intuitive. In particular,

• Multiple adjacent Delims are replaced by a single one. (The grammar above doesn't permit adjacent Delims, but they can be produced by the desugaring rules.)

• The Vesta SDL syntax allows the arbitrary intermingling of ``/'' and ``\'' as arc separators. However, the implementation actually requires that Vesta programs use one or the other uniformly. When creating a filename from a sequence of Arcs and Delims, the implementation inserts the appropriate arc separator required by the underlying file system. The choice is not influenced by the choice of Delim that appears in the Vesta SDL program.

• The grammar permits an Arc to be an arbitrary Text. An Arc in a filename, however, is forbidden to contain a Delim character (i.e., forward or backward slash), and the Arcs ``..'' and ``.'' are forbidden in filenames as well. In particular, ``..'' cannot be used to mean parent directory and ``.'' cannot be used to mean current directory. The ``..'' notation is forbidden for technical reasons related to Vesta caching, while the ``.'' notation is simply unimplemented. However, the empty Arc ``'' can be used to denote the current directory.