As a side note, it is possible to define your own "unsized" slice type which wraps `[u8]`. This can be useful for binary serialization formats which can be subdivided / sliced into smaller data units.
I don’t think any other languages do that. Instead, most of them are implementing as much as they can while viewing the storage as a blob of UTF8/UTF16 bytes/words, and throw exceptions from the methods which interpret the data as codepoints.
Strings are used a lot in all kinds of APIs. For instance, strings are used for file and directory names. The OS kernels don’t require these strings to be valid UTF-8 (Linux) or UTF-16 (Windows).
To address the use case, Rust standard library needs yet another string type, OsString. This contributes to complexity and learning curve.
So, they offloading complexity to programmers. Being such a programmer, I don’t like their attitude.
> other languages will fail at runtime
In practice, other languages usually printing squares, or sometimes character escape codes after backslash, for encoding errors in their strings. That’s not always the best thing to do, but I think that’s what people want in majority of use cases.
The only choice is whether it's explicit and managed by the language, or hidden, and you need knowledge and experience to handle it yourself without language's help. If you want "squares" for broken encoding, Rust has `to_string_lossy()` for you. It's explicit, so you won't get that error by accident.
Avoiding "mojibake" in other languages is usually a major pain. For example, PHP is completely hands-off when it comes to string encodings. To actually encode characters properly you need to know which ini settings to tweak, remember to use mb_ functions when appropriate, and don't lose track of which string has what encoding. There's internal encoding, filesystem encoding, output encoding, etc. They may be incompatible, but PHP doesn't care and won't help you.
I would want it to be implicit.
Ideally, for rare 20% of cases when I care about UTF encoding errors, I’d want a compiler switch or something similar to re-introduce these checks, but I can live without that.
> For example, PHP
When you compare Rust with PHP it’s no surprise Rust is better, many people think PHP is notoriously bad language: https://eev.ee/blog/2012/04/09/php-a-fractal-of-bad-design/
I like C# strings the best, but I also have lots of experiencer with C++, and some experience with Java, Objective-C, Python, and a few others. None of them have Rust’s amount of various string types exposed to programmers, many higher-level languages have exactly 1 string type.
Interestingly, some dynamic languages like swift use similar stuff internally, but they don’t expose the complexity to programmers, they manage to provide a higher-level abstraction over the memory layout. Compared to Rust, improves usability a lot.
Then simply use the `lossy` function. Or create an alias to it if you don't like the name.