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It's the first time since I'm alive a language that is higher level than C/C++ can compete with C/C++ in the benchmarks. If you have experienc with large C++ c

It's the first time since I'm alive a language that is higher level than C/C++ can compete with C/C++ in the benchmarks. If you have experienc with large C++ code bases you probably know how impossible it is to write safe code. Also after you use only unique/linear types, single inharitance (which is advised when working with a big code base), you are writing something that's easier to express in Rust than in C/C++. Inlined asm will stay of course, Rust doesn't try compete with it.

blub 9y ago
Safety is many shades of grey instead of being black and white and it is intertwined with the concept of risk. The fact that large C and C++ code bases exist and the products they drive are successful proves that it is possible to write code in those languages that offers a good enough risk/reward balance. This is what many Rust fans are missing: you want to sell 100% memory safety, but you're assuming that everyone wants 100% instead of 80 or 90% and that they're willing to pay the price of switching.
- steveklabnik 9y ago
  If you want to work in a memory-unsafe superset, you can; that's what unsafe is.
  - blub 9y ago
    It looks like you didn't understand what I meant. Each company/project/person needs to make a decision: * I can work in C and C++, which I can get to X% safe using the techniques and tools A, B, C at the cost of M. OR * I can invest in learning Rust and integrating it with my environment to get to 100% at the cost of N. Is the difference from X% to 100% big enough to pay N instead of M? How big of an X do I need? Is it even possible for me to use A, B and C? This is how an informed decision would look like, but Rust proponents just keep repeating that X < 100.
    - rcxdude 9y ago
      Not saying there's a cost-benefit analysis to be done, but there's a pretty nonlinear jump from under 100% to 100%, however. In my experience existing tooling for static analysis on C and C++ tends to be it can point out a lot of bugs, but it can't prove that there's are not bugs (of a particular class). This helps me catch things I miss, but it doesn't free me up from worrying about them (X% safe doesn't been I don't have to worry about X% of the code, which would be great, it means all of the code has a (1 - X%) chance of containing a safety bug, which is far less useful). This cost-benefit analysis also is substantially different between switching an existing codebase and starting a new one. The fact that Mozilla considers it worthwhile to switch an extremely large C++ codebase to Rust is worth noting.
    - steveklabnik 9y ago
      Yeah, we mean slightly different things. I agree with what you're saying, but what I'm saying is about the cost of N; if you find yourself fighting with Rust's rules, you can drop back to unsafe, and use the rules you already know. Well, similar ones anyway. This reduces the cost of N.
      - blub 9y ago
        N however can only be decreased by improving Rusts UX. If one is able to write unsafe code in Rust, they already paid the full N.

blub 9y ago

Safety is many shades of grey instead of being black and white and it is intertwined with the concept of risk. The fact that large C and C++ code bases exist and the products they drive are successful proves that it is possible to write code in those languages that offers a good enough risk/reward balance. This is what many Rust fans are missing: you want to sell 100% memory safety, but you're assuming that everyone wants 100% instead of 80 or 90% and that they're willing to pay the price of switching.

steveklabnik 9y ago
If you want to work in a memory-unsafe superset, you can; that's what unsafe is.
- blub 9y ago
  It looks like you didn't understand what I meant. Each company/project/person needs to make a decision: * I can work in C and C++, which I can get to X% safe using the techniques and tools A, B, C at the cost of M. OR * I can invest in learning Rust and integrating it with my environment to get to 100% at the cost of N. Is the difference from X% to 100% big enough to pay N instead of M? How big of an X do I need? Is it even possible for me to use A, B and C? This is how an informed decision would look like, but Rust proponents just keep repeating that X < 100.
  - rcxdude 9y ago
    Not saying there's a cost-benefit analysis to be done, but there's a pretty nonlinear jump from under 100% to 100%, however. In my experience existing tooling for static analysis on C and C++ tends to be it can point out a lot of bugs, but it can't prove that there's are not bugs (of a particular class). This helps me catch things I miss, but it doesn't free me up from worrying about them (X% safe doesn't been I don't have to worry about X% of the code, which would be great, it means all of the code has a (1 - X%) chance of containing a safety bug, which is far less useful). This cost-benefit analysis also is substantially different between switching an existing codebase and starting a new one. The fact that Mozilla considers it worthwhile to switch an extremely large C++ codebase to Rust is worth noting.
  - steveklabnik 9y ago
    Yeah, we mean slightly different things. I agree with what you're saying, but what I'm saying is about the cost of N; if you find yourself fighting with Rust's rules, you can drop back to unsafe, and use the rules you already know. Well, similar ones anyway. This reduces the cost of N.
    - blub 9y ago
      N however can only be decreased by improving Rusts UX. If one is able to write unsafe code in Rust, they already paid the full N.