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Rust has a nice solution of having a &str slice (equivalent of C++ std::string_view) as the lowest common denominator and a deref operator that can easily coerc
by pornel 3y ago
Rust has a nice solution of having a &str slice (equivalent of C++ std::string_view) as the lowest common denominator and a deref operator that can easily coerce various string types to the slice.
This allows Rust to have all kinds of string flavors (fixed-len or NUL-terminated or growable, on stack or heap or in ROM, with SSO, with CoW, interned or refcounted, atomically or not, and so on), but they all coerce to the basic &str, so they have the same basic methods, and are compatible with most functions that just want a string without caring how it's allocated.
You can use your own weird string type if you want, but usually you're not forced to convert or copy it to use it with standard library functions or 3rd party dependencies.
- josephg 3y agoYeah - although the cost of this is that it makes rust harder to learn. (Try answering the common beginner question: “How is &String different from &str?”) In rust Strings are usually passed in to functions as a &str, and returned from functions as String. It makes sense once you’re used to it, but I think philosophically Rust is much closer to C++ than C. Rust is missing the elegant minimalism of C or Zig.
- iknowstuff 3y agoSimple is a lie: https://fasterthanli.me/articles/i-want-off-mr-golangs-wild-ride#simple-is-a-lie https://fasterthanli.me/articles/i-want-off-mr-golangs-wild-...
- pepa65 3y agoOP is not talking about Golang.
- iknowstuff 3y agoThe same critique applies
- pepa65 3y agoSo Zig is not simple but Rust is? The article you ref is not talking about Zig at all by the way.
- iknowstuff 3y agoIt just illustrates the point. There is no elegance in simplicity. Zig is not memory safe and its functions „assume” utf8 with UB when they encounter invalid bytes.
- duped 3y ago> Try answering the common beginner question: “How is &String different from &str?” This has nothing to do with strings though - how is &Vec<T> different from &[T] or &Box<[T]>? You need to understand ownership, references, and unsized types.
- josephg 3y ago> This has nothing to do with strings Sort of. It certainly affects strings, and you can't really use strings without understanding the difference. My point is that its yet another thing in the big bucket of junk you need to learn in order to use rust effectively. Rust is the only language I know of that has separate types for owned strings and a borrowed strings. Its a powerful concept - and its fast and efficient for the computer. But its not "free". The cost is that it makes it harder to learn rust. While we're on the topic - it also really doesn't help that the names of these types in the standard library are super idiosyncratic. String is to Vec<u8> as &str is to &[u8]. You just have to memorise that. How about Path and PathBuf? One of them is like String, and one is like &str. I swear I have to look it up every single time. I think the investment is worthwhile - I adore rust. But as I said, rust feels more like a better C++ than a better C. All the pain is front loaded, with the assumption that you'll eventually write enough software in rust to make the investment worthwhile. Simpler languages like Python or Go get out of your way immediately and let you be productive. I prefer rust, but there's definitely something to be said for that attitude.
- bobbylarrybobby 3y agoAgree that the naming is pretty bad, but ultimately there are like… three or four of these owned/deref pairs you actually have to remember in day to day usage? I do wish they had gone with a consistent naming scheme, but in the grand scheme of things this is one of the more minor things that Rust got wrong.
- duped 3y agoI think I would sum this up with saying that strings are not simple, and there is a delicate balance between making simple things simple and complex things possible without shooting yourself in the foot - both as a user, and as a library designer. Since Rust prefers to have verbosity and correctness over ease, it makes sense to have multiple types to reflect the different requirements of the underlying data. I sympathize with some of the std library verbosity when it comes to strings (and paths) but I don't think it's really a big criticism of why Rust's learning curve is steep. You have the same issues in C++, and doubly so in C because it doesn't help you at all and when you screw up the program crashes. When you use strings in an unmanaged language and need to manipulate them, you do need to understand the underlying consequences of how those strings are defined and stored. Comparing to managed languages like Python and Go is a bit unfair, because they're working in a different domain. Python is a great example of what happens when you try and hide complexity too far from the programmer - the python3 ecosystem fracture took millions of dollars and over a decade to settle - because of the inherent complexity in string representations. > Rust is the only language I know of that has separate types for owned strings and a borrowed strings. C++ and Objective-C (kinda) have different types for owned and referenced strings. C++ in particular has the same requirements as Rust, where referenced strings need to be able to refer to literals and it's not acceptable to make the default allocate.
- pornel 3y agoC also has &str and &String, but they're "char* that crashes if you free() it" and "char* that leaks if you don't free() it". Ownership is hard to learn, and it is a barrier to learning Rust. However, don't confuse it with C++. Rust has two+ string types on purpose, not because of carrying 1970's legacy.
- neonsunset 3y agoYup, I can’t imagine switching to a language that doesn’t have something like that, since in C# you have a similar feature in the form of Span<T> and ReadOnlySpan<T>, to which all manners of sources can be coerced: heap-allocated arrays, stack-allocated buffers, inline arrays, strings, native memory, etc.