4 ms·

Yes, I understand that. I'm saying I don't understand why the Rust community has made that choice, since it essentially makes old versions of the compiler usele

Yes, I understand that. I'm saying I don't understand why the Rust community has made that choice, since it essentially makes old versions of the compiler useless and therefore makes it difficult for software written in Rust to be part of a typical Linux distribution. (And has a number of other disadvantages too, like constant cognitive load having to re-learn the language every 6 weeks). Also, editions could be a snapshot of the language definition at a point in time, without being a snapshot of the compiler. There are still new versions of Clang and GCC coming out with new bugfixes, better optimizations, improved error messages, support for different hardware, WIP support for future language editions, etc., without changing the C++17 standard.

jcranmer 7y ago
> (And has a number of other disadvantages too, like constant cognitive load having to re-learn the language every 6 weeks). While the cadence may be faster, the pace of language change in Rust is slower than other popular languages such as C++ or JS.
- pjmlp 7y ago
  How come, given that currently C++ has three years to release a new standard and then about the same until the latest release gets spread around all major compilers? https://en.cppreference.com/w/cpp/compiler_support https://en.cppreference.com/w/cpp/compiler_support Right now with C++20 around the corner, C++14 is still the safest bet for portable code, whereas in Rust we still see relevant crates that depend on nightly.
  - jcranmer 7y ago
    Here is the list of all the major features added to Rust since 1.0: * The new lifetime model (non-lexical lifetimes) * Async fn * Procedural macros * ? operator * Import name resolution changes * impl Trait * C-style unions Here's the list of features added in C++17 and C++20: * constexpr if * Modules * Structured binding * Type deduction helpers * Coroutines * <=> operator * Concepts * Expanded the set of expressions and statements that qualify as constexpr to the point that it's a very different feature from what it was in C++11. In the same amount of time, C++ has added roughly the same number of features, but I would qualitatively say that C++'s feature additions are more impactful than Rust's feature additions, especially in terms of making newer code unrecognizable to programmers used only to the old version. That's what I meant by pace versus cadence--overall, C++ has changed more, but it tends to change in triennial bursts instead of every six weeks.
    - pjmlp 7y ago
      The difference being that C++ developers have around 6 years time to get acquainted with each version. The 3 years for each ISO revision, plus around three until the standard is actually usable in a portable way. My old dusty non-maintained MFC applications still compile on latest Visual Studio.
  - umanwizard 7y ago
    > C++14 is still the safest bet for portable code There are supported versions of RHEL that still only support C++11, FWIW.
    - pjmlp 7y ago
      True, but those are the same ones stuck on Java 1.4. :(
kibwen 7y ago
> I don't understand why the Rust community has made that choice, since it essentially makes old versions of the compiler useless I mention the reason in my prior comment: to allow people to continually upgrade their compiler version without needing to change any code. Rust doesn't have a stable ABI, so all crates in a Rust project ultimately need to be built with the same compiler (and furthermore, crates must always be able to interoperate regardless of which edition they're on). That means that every new version of the compiler needs to support every old edition, because the alternative is to have users stuck on old versions of not just the compiler but also on old versions of dependencies that have since begun using features only supported by newer compilers. In Rust's case avoiding such a fundamental fracture in the community was more important, since, after all, there's still nothing stopping anyone from voluntarily sticking with an older version of the compiler if they're willing to deliberately endure such a situation. > (And has a number of other disadvantages too, like constant cognitive load having to re-learn the language every 6 weeks). This is quite hyperbolic. Rust introduces no more features than any other language, it simply rolls them out on a more fine-grained schedule. Furthermore, Rust hardly requires re-learning every six weeks; a "feature" introduced by a new version is often nothing more than a new convenience method in the standard library. The fact that we have established that Rust goes out of its way even to keep "old" code compiling and compatible with the rest of the ecosystem should demonstrate how little it demands that users re-learn anything.

jcranmer 7y ago

> (And has a number of other disadvantages too, like constant cognitive load having to re-learn the language every 6 weeks). While the cadence may be faster, the pace of language change in Rust is slower than other popular languages such as C++ or JS.

pjmlp 7y ago
How come, given that currently C++ has three years to release a new standard and then about the same until the latest release gets spread around all major compilers? https://en.cppreference.com/w/cpp/compiler_support https://en.cppreference.com/w/cpp/compiler_support Right now with C++20 around the corner, C++14 is still the safest bet for portable code, whereas in Rust we still see relevant crates that depend on nightly.
- jcranmer 7y ago
  Here is the list of all the major features added to Rust since 1.0: * The new lifetime model (non-lexical lifetimes) * Async fn * Procedural macros * ? operator * Import name resolution changes * impl Trait * C-style unions Here's the list of features added in C++17 and C++20: * constexpr if * Modules * Structured binding * Type deduction helpers * Coroutines * <=> operator * Concepts * Expanded the set of expressions and statements that qualify as constexpr to the point that it's a very different feature from what it was in C++11. In the same amount of time, C++ has added roughly the same number of features, but I would qualitatively say that C++'s feature additions are more impactful than Rust's feature additions, especially in terms of making newer code unrecognizable to programmers used only to the old version. That's what I meant by pace versus cadence--overall, C++ has changed more, but it tends to change in triennial bursts instead of every six weeks.
  - pjmlp 7y ago
    The difference being that C++ developers have around 6 years time to get acquainted with each version. The 3 years for each ISO revision, plus around three until the standard is actually usable in a portable way. My old dusty non-maintained MFC applications still compile on latest Visual Studio.
- umanwizard 7y ago
  > C++14 is still the safest bet for portable code There are supported versions of RHEL that still only support C++11, FWIW.
  - pjmlp 7y ago
    True, but those are the same ones stuck on Java 1.4. :(

kibwen 7y ago

> I don't understand why the Rust community has made that choice, since it essentially makes old versions of the compiler useless I mention the reason in my prior comment: to allow people to continually upgrade their compiler version without needing to change any code. Rust doesn't have a stable ABI, so all crates in a Rust project ultimately need to be built with the same compiler (and furthermore, crates must always be able to interoperate regardless of which edition they're on). That means that every new version of the compiler needs to support every old edition, because the alternative is to have users stuck on old versions of not just the compiler but also on old versions of dependencies that have since begun using features only supported by newer compilers. In Rust's case avoiding such a fundamental fracture in the community was more important, since, after all, there's still nothing stopping anyone from voluntarily sticking with an older version of the compiler if they're willing to deliberately endure such a situation. > (And has a number of other disadvantages too, like constant cognitive load having to re-learn the language every 6 weeks). This is quite hyperbolic. Rust introduces no more features than any other language, it simply rolls them out on a more fine-grained schedule. Furthermore, Rust hardly requires re-learning every six weeks; a "feature" introduced by a new version is often nothing more than a new convenience method in the standard library. The fact that we have established that Rust goes out of its way even to keep "old" code compiling and compatible with the rest of the ecosystem should demonstrate how little it demands that users re-learn anything.