Section 3.3 "File system" defines a whole bunch of procedures which
take a fname/fd/port as argument and call to file-info and inspect the
file-info record (file-type...file-last-status-change,
file-not-readable?...file-executable). The file-info record however is
not passed to the outside so that subsequent operations on the same
file will call file-info again and again which means a huge performance
First calling file-info and operating on the obtained record
afterwards means far less overhead but is also less comfortable since
the procedures mentioned above do not exist.
I think we can easily remedy this by allowing the mentioned procedures
to accept a file-info record as argument.