How robust / feature-complete is Cascadia Mono's Arabic script support?

[lancejpollard]

How robust is the implementation of Arabic monospace in Cascadia Mono? Unbelievable you guys have done this! Doesn't come up on search results really that Cascadia has Arabic monospace support :D there's only like 2 other partial implementations I can see so far on the web out there.

But can't really rely on it fully if it's missing major things, not sure what the fallback behavior will be like or how common it would be for users, etc.. So would like to know more if possible. Thank you. Here's what I've seen so far....

Arabic + Unicode Scope

Looks like Unicode Arabic has Arabic symbols as of Unicode v17.0 in what like 11 blocks:

1. Arabic
2. Arabic Supplement
3. Arabic Extended-B
4. Arabic Extended-A
5. Arabic Presentation Forms-A
6. Arabic Presentation Forms-B
7. Rumi Numeral Symbols
8. Arabic Extended-C
9. Indic Siyaq Numbers
10. Ottoman Siyaq Numbers
11. Arabic Mathematical Alphabetic Symbols

Debugging Cascadia Mono Arabic Support (a little 😊)

Only way I can tell if all are supported is plugging them into the Google fonts tester, hence my question haha.

One random check on Arabic Extended-A shows some missing, and all currently missing in italic style:

Tangent: Saw italics missing on Hebrew support too, but might ask about that more specifically later, unless you know real quick too.

FWIW this is what Arabic Extended-A wiki page looks like on my M3 MacBook:

Many characters still missing by default, so I guess I am not concerned about EVERY unicode character, mainly only really wondering if there is basically feature-parity with OS-level/standard Arabic fonts, whatever amount of unicode subset they have ended up currently supporting so far.

Or if there's a big gap between what Cascadia Mono (Arabic) supports vs. what standard/OS-level fonts typically support?

Note: I'm aware of the ~800+ deprecated Arabic "presentation forms" in unicode (were for compatibility with older standards such as something for DOS and such I guess, according to Wikipedia), so don't care about those, we shouldn't be writing with those I don't think.

Basic Arabic Glyphs Missing

Plugging in this into the Google font tester (everything from base block):

 ؀ ؁ ؂ ؃ ؄ ؅ ؆ ؇ ؈ ؉ ؊ ؋ ، ؍ ؎ ؏
ؐ ؑ ؒ ؓ ؔ ؕ ؖ ؗ ؘ ؙ ؚ ؛ ؝ ؞ ؟
ؠ ء آ أ ؤ إ ئ ا ب ة ت ث ج ح خ د
ذ ر ز س ش ص ض ط ظ ع غ ػ ؼ ؽ ؾ ؿ
ـ ف ق ك ل م ن ه و ى ي ً ٌ ٍ َ ُ
ِ ّ ْ ٓ ٔ ٕ ٖ ٗ ٘ ٙ ٚ ٛ ٜ ٝ ٞ ٟ
٠ ١ ٢ ٣ ٤ ٥ ٦ ٧ ٨ ٩ ٪ ٫ ٬ ٭ ٮ ٯ
ٰ ٱ ٲ ٳ ٴ ٵ ٶ ٷ ٸ ٹ ٺ ٻ ټ ٽ پ ٿ
ڀ ځ ڂ ڃ ڄ څ چ ڇ ڈ ډ ڊ ڋ ڌ ڍ ڎ ڏ
ڐ ڑ ڒ ړ ڔ ڕ ږ ڗ ژ ڙ ښ ڛ ڜ ڝ ڞ ڟ
ڠ ڡ ڢ ڣ ڤ ڥ ڦ ڧ ڨ ک ڪ ګ ڬ ڭ ڮ گ
ڰ ڱ ڲ ڳ ڴ ڵ ڶ ڷ ڸ ڹ ں ڻ ڼ ڽ ھ ڿ
ۀ ہ ۂ ۃ ۄ ۅ ۆ ۇ ۈ ۉ ۊ ۋ ی ۍ ێ ۏ
ې ۑ ے ۓ ۔ ە ۖ ۗ ۘ ۙ ۚ ۛ ۜ ۝ ۟
۠ ۡ ۢ ۣ ۤ ۥ ۦ ۧ ۨ ۩ ۪ ۫ ۬ ۭ ۮ ۯ
۰ ۱ ۲ ۳ ۴ ۵ ۶ ۷ ۸ ۹ ۺ ۻ ۼ ۽ ۾ ۿ

Looks like some stuff is off/missing, thoughts?

(with removing all spaces, this is what it looks like):

Summary

Actually it looks like only the first 4 blocks there show up for me on Wikipedia, so 🤷:

1. Arabic
2. Arabic Supplement
3. Arabic Extended-B
4. Arabic Extended-A

All the rest are blank boxes, so guess it's just that? Looks like "most common stuff" is supported? Not sure about the missing ones.

But I don't have deep or practical knowledge of Arabic script totally yet, so not sure about all the edge cases of:

• combining diacritics
• ligatures

So yeah, if you could outline what the missing pieces are (beyond italics), that would be great. If you also happen to know if it's something that will be planned in future that would be interesting to know too, thank you so much. Insane you guys accomplished this, major feat for sure!