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> because certain types of silly mistakes I tend to make in Python and C just wouldn't compile. Python and C are similar in that regard. You can compile almost

> because certain types of silly mistakes I tend to make in Python and C just wouldn't compile. Python and C are similar in that regard. You can compile almost anything in them. Will then crash in runtime if not OK, gracefully for Python, the whole process for C. Languages like Java or C# are different. Both are strongly typed, a lot of things are checked by compilers. I believe C# is safer than Rust because native code surface is much smaller. Safe Rust is fundamentally limited by that borrow checker. Read the source of Rust standard library, you'll see tons of unsafe code everywhere. Rust developers probably did a good job verifying their implementations of stuff like Vec and HashMap, but there're less used parts of the standard library. Non-standard third-party libraries also using unsafe. .NET doesn't need any unsafe code for such things. Even fundamental parts of the standard library, like List and Dictionary, are 100% managed code, to be specific it's C#: https://github.com/dotnet/coreclr/blob/master/src/System.Private.CoreLib/shared/System/Collections/Generic/List.cs https://github.com/dotnet/coreclr/blob/master/src/System.Pri... Same is true for majority of third-party libraries: unsafe is supported by the languages, but using it may complicate deployment.

steveklabnik 7y ago
The standard library has far more unsafe code than an average Rust project. One of the major reasons why is “needs a lot of unsafe to implement” is a historical criteria for “this belongs in the standard library”.
- Const-me 7y ago
  > One of the major reasons why is “needs a lot of unsafe to implement” is a historical criteria for “this belongs in the standard library” Custom data structures often need a lot of unsafe code. Graphs, trees and linked lists are everywhere in system programming. You can’t add everything to standard library, too many variations. For trees, in C++ and/or C# I’ve used red-black, B-tree, unordered, and multi-dimensional ones like BSP, k-d, and PK. Graphs are all different, depending on what you need to store (just the topology, per-node data, per-edge data), and which operations need to work fast on them. Even linked lists are different, sometimes you want single link, other times you want them to be circular instead of linear. And there’re other pointer-based structures useful for some applications, like skip lists and tries.
  - steveklabnik 7y ago
    Thanks to generics and the ease of publishing packages, those aren’t usually “custom” in Rust programs; you import a package that has them implemented for you. Just like you import ones from the standard library. Even then, that’s still a very small amount of the overall code in a given project.
    - Const-me 7y ago
      > those aren’t usually “custom” in Rust programs On modern hardware, RAM latency is often the main reason why CPU-bound code is slow. The fix is often changing RAM layout, i.e. modifying data structures. And when the code uses SIMD to process the payload portion of these structures, alignment requirements cause them to become really custom pretty soon. > that’s still a very small amount of the overall code in a given project That’s not universal across all software. Lately, I’m working in the area of CAD/CAM/CAE. Before that I worked on videogames, HPC, multimedia. In many of these projects, data structures were not a small amount, even relatively speaking.
atoav 7y ago
The Standard library has to use unsafe because of performance considerations, it is extremely well tested for that reason. I wrote multiple projects in Rust and I never had to use unsafe even once. Arguably all these projects weren’t all that lowlevel, but why would I write something that somebody else has already implemented and tested? The beauty of Rust, after all is that you can go to the lowest level if you like to, but you can stay high level if you like and you still end up with code that is surprisingly performant.
- Const-me 7y ago
  > has to use unsafe because of performance considerations Java and C# solved this problem without unsafe, with JIT compilers. > The beauty of Rust, after all is that you can go to the lowest level if you like to, but you can stay high level if you like All sufficiently complex systems are written in more than one language. Operating systems are written in C and C++, have shell scripting running on top. Videogames are written in C++, they have integrated script engines or VMs for higher-level stuff. Productivity software like MS office or AutoCAD have script engines. No single language does the job. It’s not just performance versus safety tradeoff. These higher-level languages are much easier to learn, meaning developers are cheaper, and in many cases like VBA even non-developers can do stuff done with them. They often aren’t compiled or compile very fast, this makes iterations faster and allows interactive prototyping. They often run in sandboxes, solving security issues. I don’t program in Rust, but I’ve read quite a lot about it. And I program C++ and C# for decades, often in the same software at the same time. IMO C++ is better at lower-level things: tooling, SIMD, manual control over RAM layout, better at creating fast data structures, OpenMP, has way better libraries (e.g. in the current project I use Eigen a lot, it’s based on C++ metaprogramming i.e. not portable to anything else). C# is better for everything else: it’s safer, has way better libraries included (e.g. async IO is awesome), is higher level, for the last couple of years it’s cross-platform and open source, and is much easier to use.

steveklabnik 7y ago

The standard library has far more unsafe code than an average Rust project. One of the major reasons why is “needs a lot of unsafe to implement” is a historical criteria for “this belongs in the standard library”.

Const-me 7y ago
> One of the major reasons why is “needs a lot of unsafe to implement” is a historical criteria for “this belongs in the standard library” Custom data structures often need a lot of unsafe code. Graphs, trees and linked lists are everywhere in system programming. You can’t add everything to standard library, too many variations. For trees, in C++ and/or C# I’ve used red-black, B-tree, unordered, and multi-dimensional ones like BSP, k-d, and PK. Graphs are all different, depending on what you need to store (just the topology, per-node data, per-edge data), and which operations need to work fast on them. Even linked lists are different, sometimes you want single link, other times you want them to be circular instead of linear. And there’re other pointer-based structures useful for some applications, like skip lists and tries.
- steveklabnik 7y ago
  Thanks to generics and the ease of publishing packages, those aren’t usually “custom” in Rust programs; you import a package that has them implemented for you. Just like you import ones from the standard library. Even then, that’s still a very small amount of the overall code in a given project.
  - Const-me 7y ago
    > those aren’t usually “custom” in Rust programs On modern hardware, RAM latency is often the main reason why CPU-bound code is slow. The fix is often changing RAM layout, i.e. modifying data structures. And when the code uses SIMD to process the payload portion of these structures, alignment requirements cause them to become really custom pretty soon. > that’s still a very small amount of the overall code in a given project That’s not universal across all software. Lately, I’m working in the area of CAD/CAM/CAE. Before that I worked on videogames, HPC, multimedia. In many of these projects, data structures were not a small amount, even relatively speaking.

atoav 7y ago

The Standard library has to use unsafe because of performance considerations, it is extremely well tested for that reason. I wrote multiple projects in Rust and I never had to use unsafe even once. Arguably all these projects weren’t all that lowlevel, but why would I write something that somebody else has already implemented and tested? The beauty of Rust, after all is that you can go to the lowest level if you like to, but you can stay high level if you like and you still end up with code that is surprisingly performant.

Const-me 7y ago
> has to use unsafe because of performance considerations Java and C# solved this problem without unsafe, with JIT compilers. > The beauty of Rust, after all is that you can go to the lowest level if you like to, but you can stay high level if you like All sufficiently complex systems are written in more than one language. Operating systems are written in C and C++, have shell scripting running on top. Videogames are written in C++, they have integrated script engines or VMs for higher-level stuff. Productivity software like MS office or AutoCAD have script engines. No single language does the job. It’s not just performance versus safety tradeoff. These higher-level languages are much easier to learn, meaning developers are cheaper, and in many cases like VBA even non-developers can do stuff done with them. They often aren’t compiled or compile very fast, this makes iterations faster and allows interactive prototyping. They often run in sandboxes, solving security issues. I don’t program in Rust, but I’ve read quite a lot about it. And I program C++ and C# for decades, often in the same software at the same time. IMO C++ is better at lower-level things: tooling, SIMD, manual control over RAM layout, better at creating fast data structures, OpenMP, has way better libraries (e.g. in the current project I use Eigen a lot, it’s based on C++ metaprogramming i.e. not portable to anything else). C# is better for everything else: it’s safer, has way better libraries included (e.g. async IO is awesome), is higher level, for the last couple of years it’s cross-platform and open source, and is much easier to use.