Arguably one of those cases where the capability is awesome, but using the capability is wat.
replyI mean, fonts are Turing-complete [0], so it isn’t surprising that this is possible. Turing-completeness is often by accident rather than by genius [1].
reply[0] https://litherum.blogspot.com/2019/03/addition-font.html
[1] https://en.wikipedia.org/wiki/Turing_completeness#Unintentio...
Which makes sense, because human language is apparently Turing complete, so anything intended to represent it faithfully would wind up with that characteristic, too.
replyHuman language isn’t a formal language, so this is a category error.
replyIn the present context, an example is that the common reading of a Kanji word isn’t always well-defined, and neither is the decomposition of a sequence of Kanji characters into words.
It's often used as one, though.
replyNo, it’s not? https://en.wikipedia.org/wiki/Formal_language#Definition
replyIt's an interesting move to point me to a rigorously written English language definition of a formal language to make the argument that humans don't co-opt our natural languages as formal languages when the need arises.
replyThat’s not what “formal language” means. English being used to describe a formal definition doesn’t make it a formal language.
replyI didn’t say it was a formal language, I said humans co-opt it as one.
replyBitmap fonts aren't turing complete. The fact that TrueType is built with an arbitrary virtual machine is insane, makes implementations ridiculously complex, and is a huge security liability. The purpose of the VM wasn't to "represent human language faithfully" but to make fonts look a little better when displayed at a variety of resolutions, via hinting. Hinting doesn't necessarily require a full VM, but somebody let the engineers have a little too much fun.
replyAnd yet, actually mapping all written human languages and their ligatures, variations, etc, seems to require this level of complexity. So the choice is either you draw the line and decide which languages you consider legitimate or not, or you build a machine of sufficient complexity to capture all languages, and the tradeoff, I suppose, is how much knowledge you want to actually be able to capture in your computerized system.
replyUnicode is distinct from, and completely unrelated to, TrueType. Unicode does not require a virtual machine to interpret. You can simply express languages and their variations with Unicode + bitmap fonts.
replyUnless you want ligatures.
replyDo you really believe the only way to implement ligatures is with a virtual machine? Dumb and dirty psuedocode written in 5 seconds of thinking about it but come on, this is not that complicated.
reply for each character in text
characterToPrint = Parse(character)
if character is LigatureStartCandidate
characterToPrint = LookAheadForNextLigatureCandidateAndResolve(character)
Print(characterToPrint)And you've now gotten 92% of the way there. Iterate a few dozen more times to get up to 97%, 98%, 99%, etc., and eventually you'll have rewritten OpenType.
replyWould you like to elaborate on those few dozen more cases rather than handwaving them away? Embedding a VM into a font format is foundationally a ridiculous idea and should require real justification, although I know our industry is in love with anything that allows arbitrary code execution exploits.
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