alt Hacker NewsUTF-8000: Unlimited UTF-8
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On a practical matter, it seems like a bad idea to have codepoints that can take up to an arbitrary number of bytes - this just screams buffer overflow problems.
So in practicality, you’re going to want an arbitrary limit on this (the article suggests as much). But if you place a limit on it then you’ve got one implementation of the standard that can decode certain characters and another that can’t. Better to have one standard that puts a hard limit on the number of bytes and another standard that uses more bytes and so on.
UTF-8 originally supported up to six-byte encodings (see eg. RFC 2279), but it was restricted to four bytes in 2003 in order to match UTF-16 constraints :(
Some ideas of what to do with this space:
- fully-customizable emojis (think of a RPG-like character customization screen)
- heck, why not full jpegs/gifs?
- some unicode programming script (running Doom)
- ?
That said, some very minor (HN-style) nitpick:
> Otherwise for an n byte code unit this is (5n+1) / 8n, that is 5n+1 content bits out of a total of 8n bits from n bytes. We can rewrite this as (5/8) + 1/(8n) which moderately quickly approaches 5/8 = 62.5%. It is nice that this limit is nonzero and does not depend on n.
Isn't a limit by definition no longer dependent on n?
> UTF-8000 is in no way endorsed by or representative of the Unicode Consortium.
Not until they decide to expand the emoji range, allocate space for all past and future fictional languages, as well as birdsong and dog barks.
Someone at the consortium is rubbing their hands with glee with all the newfound space.
But honestly, cool hack! If you invent a method to encode large numbers into bytes, why limit yourself to 24-bit numbers?
> Ken Thompson: "...i really dont think it is useful. it is like replacing ipv6 with ipv50"
Just limit it to 8 bytes at which point you always do 'know the number of follow on bytes' from the first byte.
Nobody needs more than 4.47 trillion characters. (famous last words)
Self-synchronization in UTF-8 is intuitively a great thing to have, yet I don’t remember actively relying on it ever. Does anyone have a good example of when it‘s useful?
Another related nice property that UTF-8 has: substring search reduces to bytestring substring search. I.e. given two Unicode strings in UTF-8 encoding, you can check if one is a substring of the other by just treating them as bytestrings and checking if one bytestring is a substring of the other bytestring. This is a stronger property than self-synchronization: UTF-8 has it, but UTF-8000 doesn’t.
FF bytes are an easy way to identify an invalid UTF-8 file. This idea doesn't have that property.
This is like TIME CUBE (https://en.wikipedia.org/wiki/Time_Cube) but for encoding nerds.
edit: replaced false prophet site with wiki link for the original one and true timecube.com...lost to the sands of ...time.
The letter from Ken Thompson is spot on:
"your first 2 extensions (5 and 6 bytes) were clearly envisioned. the standard (up to 4 bytes) was created to cover the size of unicode. i thought any more description would be a waste of paper. i think your extension from 7 to 8 bytes is a little hoaky. i requires reading the whole string rather than "knowing" the number of follow on bytes. so, i think the only thing new is the 7 byte version.
i appreciate the mail, but i really dont think it is useful. it is like replacing ipv6 with ipv50."
I love it.
Some day we'll need this when we finally realise we are not alone in the universe. Alien glyphs ftw.
Phew, and I was worried that we'd be running out of UNICODE space for new emojis ;)
It would be nice if the first paragraph gave a motivation for this. Why did you start this?
I mean, I can derive from the text that this can encode arbitrarily large integers. So what? What's the point? I also understand that this is for fun.
No project is ever safe from complicators.
This is why we need the KISS enforcers.
I was about to immediately suggest UCS-X, and then pleased that the author offers a fair comparison to UCS-X and many other alternatives. Great. Too bad UCS-X is possibly more memorable name.