This is pretty parallel to a problem in URL!.
We have the problem of:
>> reverse http://hostilefork.com
== moc.krofelitsoh//:ptth
What you end up with still claims to be a URL!, but wouldn't load back as one. In fact, it would be loaded under today's conventions as a PATH!, since // denotes a BLANK! path segment. :-/
Historically the idea was that it's just a matter of noticing when something isn't rendering as a "natural" of its type, and falling back on some alternate notation. Whatever it would be, we'd hope it wouldn't be any uglier than:
#[url! "moc.krofelitsoh//:ptth"]
But as with PATH!, we can question just how useful is it to allow freaks of nature to exist vs. making them immutable and not allowing them. If you could turn URL!s into TEXT! easily enough, and turn them back, isn't that good enough?
Pieces of URL! being URL! is not that interesting. Consider being rid of the PARSE behavior of matching datatypes for COPY:
url: http://example.com/foo
parse url ["http://example.com/" copy stuff: to end]
That will now again give you STUFF as the neutral string "foo" like in Rebol2. It's not a URL! of simply "foo" (and hence really should show as #[url! "foo"]). That seems more desirable.
Is pretty much any kind of surgery on URL!s necessary? How often could one's needs not just be taken care of with JOIN-ing them...as being tried for PATH!, and convert otherwise?