3.3 library(http/http_dirindex): HTTP directory listings
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Availability::- use_module(library(http/http_dirindex)).
Source[det]http_reply_dirindex(+DirSpec, :Options, +Request)
Provide a directory listing for Request, assuming it is an index for the physical directrory Dir. If the request-path does not end with /, first return a moved (301 Moved Permanently) reply.

The calling conventions allows for direct calling from http_handler/3.