[josephg]

For context, it looks like you’re talking about iterating by grapheme clusters.

I understand how iterating through a string by grapheme clusters is convenient for some applications. But it’s far from obvious to me that doing so should be the language’s default. Dealing with grapheme clusters requires a Unicode database, which needs to live somewhere and needs to be updated continuously as Unicode grows. (Should rust statically link that library into every app that uses it?)

Generally there are 3 ways to iterate a string: by UTF8 bytes (or ucs2 code points like Java/js/c#), by Unicode codepoint or by grapheme clusters. UTF8 encoding comes up all the time when encoding / decoding strings - like, to json or when sending content over http. Codepoints are, in my opinion, the correct approach when doing collaborative editing or patching strings. And grapheme clusters are useful in frontend user interfaces - like when building a terminal.

Of those 3 iteration methods, I’ve personally used UTF8 encoding the most and grapheme clusters the least. Tell me - why should grapheme clusters be the default way to iterate over a string? I can see the argument in Swift, which is a language built for frontend UI. But in a systems language like rust? That seems like a terrible default to me. UTF8 bytes are by far the most useful representation for strings in systems code, since from the pov of systems code, strings are usually just data.

[speedyjay]

This was not meant as criticism for rust in particular (though, while it shouldn't be the default behavior of strings in a systems language, surely at least the official implementation of a wrapper should exist?), but high level languages with ton of baggage like python should definitely provide the correct way to handle strings, the amount of software I've seen that are unable to properly handle strings because the language didn't provide the required grapheme handling and the developer was also not aware of the reality of graphemes and unicode..

You mention terminals, yes, it's one of the area where graphemes are an absolute must, but pretty much any time you are going to do something to text like deciding "I am going to put a linebreak here so that the text doesn't overflow beyond the box, beyond this A4 page I want to print, beyond the browser's window" grapheme handling is involved.

Any time a user is asked to input something too. I've seen most software take the "iterate over characters" approach to real time user input and they break down things like those emojis into individual components whenever you paste something in.

For that matter, backspace doesn't work properly on software you would expect to do better than that. Put the emoji from my pastebin in Microsoft Edge's search/url bar, then hit backspace, see what happens. While the browser displays the emoji correctly, the input field treats it the way Python segments it in my example: you need to press backspace 7 times to delete it. 7 times! Windows Terminal on the other hand has the quirk of showing a lot of extra spaces after the emoji (despite displaying the emoji correctly too) and will also require 11 backspace to delete it.

Notepad handles it correctly: press backspace once, it's deleted, like any normal character.

> Of those 3 iteration methods, I’ve personally used UTF8 encoding the most and grapheme clusters the least.

This doesn't say anything about grapheme clusters being useless. I've cited examples of popular software doing the wrong thing precisely because, like you, they didn't iterate over grapheme clusters. That you never use grapheme iteration might say more about you than it says about grapheme iteration being unneeded.

The dismissiveness over more sane string handling as a standard is not unlike C++ developers pretending that developers are doing the right thing with memory management so we don't need a GC (or rust's ownership paradigm). Nonsense.

[josephg]

Those are good examples! Notably, all of them are in reasonably low level, user-facing code.

Your examples are implementing custom text input boxes (Excel, Edge), line breaks while printing, and implementing a terminal application. I agree that in all of those cases, grapheme cluster segmentation is appropriate. But that doesn't make grapheme cluster based iteration "the correct way to handle strings". There's no "correct"! There are at least 3 different ways to iterate through a string, and different applications have different needs.

Good languages should make all of these options easy for programmers to use when they need them. Writing a custom input box? Use grapheme clusters. Writing a text based CRDT? Treat a string as a list of unicode codepoints. Writing an HTTP library? Treat the headers and HTML body as ASCII / opaque bytes. Etc.

I take the criticism that rust makes grapheme iteration harder than the others. But eh, rust has truly excellent crates for that within arms reach. I don't see any advantage in moving grapheme based segmentation into std. Well, maybe it would make it easier to educate idiot developers about this stuff. But there's no real technical reason. Its situationally useful - but less useful than lots of other 3rd party crates like rand, tokio and serde.

> like you, they didn't iterate over grapheme clusters. That you never use grapheme iteration might say more about you than it says about grapheme iteration being unneeded.

It says that in 30+ years of programming, I've never programmed a text input field from scratch. Why would I? That's the job of the operating system. Making my own sounds like a huge waste of time.