6 ms·

I find it interesting that such critical code is written in C. Why not use something with a lot more (easily)statically provable properties. Like Rust or Agda?

MiroF 7y ago
Because safety critical fields are also slow-moving.
retrac 7y ago
I think the answer was right there in their comment. "The compiler for our flight hardware platform is GCC 4.1 (upgrading to GCC 4.3 soon if we're lucky)". Often, the only high-level language available for an embedded platform is a standard C compiler. If you're lucky.
NobodyNada 7y ago
Using a newer language carries a lot of risks and challenges for embedded programs: - There’s a high risk of bugs in the compiler/standard library in languages with lots of features - Usually, the manufacturer of an embedded platform provides a C compiler. Porting a new compiler can be a LOT of work, and the resulting port can often be very buggy - Even if you can get a compiler to work, many newer languages rely on a complicated runtime/standard library, which is a deal-breaker when your complete program has to fit in a few kilobytes of ROM
amw-zero 7y ago
You’ll find that for very serious, industrial applications, a conservative mindset prevails. C may not be trendy at the moment, but it powers the computing world. Its shortcomings are also extremely well known and also statically analyzable. Also, think about when flight software started being written. Was Rust an option? And once it came out, do you expect that programmers who are responsible for millions of people’s lives to drop their decades of tested code and development practices to make what is a bet on what is still a new language? What I find interesting is this mindset. My conservativeness on a project is directly proportional to its importance / criticality, and I can’t think of anything more important or critical than software that runs on a commercial airplane. C is a small, very well understood language. Of course it gives you nothing in terms of automatic memory safety, but that is one tradeoff in the list of hundreds of other dimensions. When building “important” things it’s important to think about tradeoffs, identify your biases, and make a choice that’s best for the project and the people that the choice will affect. If you told me that the moment anyone dies as a result of my software I would have to be killed, I would make sure to use the most tried-and-true tools available to me.
- AtlasBarfed 7y ago
  You're advocating throwing baby out with bathwater. Rust interops with C seamlessly, doesn't it? You don't have to throw out good code to use a better language or framework. C may be statically analyzable to some degree, but if Rust's multithreading is truly provable, then new code can be Rust and of course still use the tried and true C libraries. Disclaimer: I still haven't actually learned any Rust, so my logic is CIO-level of potential ignorance.
  - jschwartzi 7y ago
    The issue is that you’re trading a problem space that is very well understood for one that isn’t. Making a safe program in C is all about being explicit about resource allocation and controlling resources. So we tend to require that habit in development. It’s socialized. The only thing you’d be doing is using technology to replace the socialization. And you’d be adding new problems from Rust that don’t exist in the C world. It’s tempting in a lot of cases to read the data sheet and determine that the product is good enough. But there are a lot of engineering and organizational challenges that aren’t written in the marketing documents. Those challenges have to be searched for and social and technological tools must be developed to solve those challenges. As an exercise in use of technology it looks easy but there’s an entire human and organizational side to it that gets lost in discussions on HN.
  - NextHendrix 7y ago
    Wanting to suddenly start using rust would mean putting any and all tools through a tool qualification process, which is incredibly time consuming and vastly expensive. In the field of safety critical software, fancy new languages are totally ignored for, at least partially, this reason. What's really safer, a new language that claims to be "safe" or a language with a formally verified compiler and toolchain where all of your developers have decades of experience with it and lots of library code that has been put through stringent independent verification and validation procedures, with proven track record in multiple other safety critical projects?
  - prostheticvamp 7y ago
    > Disclaimer: I still haven't actually learned any Rust, so my logic is CIO-level of potential ignorance And yet you seem to write with such confidence. /Are/ you a CIO? It’s the only thing that makes sense.
bdavis__ 7y ago
Ada is used a fair amount in high $ projects. Toolchains are expensive, and the C compiler is provided for free from the chip / board vendor.
hechang1997 7y ago
Isn't Ada already used in areospace industry?

MiroF 7y ago

Because safety critical fields are also slow-moving.

retrac 7y ago

I think the answer was right there in their comment. "The compiler for our flight hardware platform is GCC 4.1 (upgrading to GCC 4.3 soon if we're lucky)". Often, the only high-level language available for an embedded platform is a standard C compiler. If you're lucky.

NobodyNada 7y ago

Using a newer language carries a lot of risks and challenges for embedded programs: - There’s a high risk of bugs in the compiler/standard library in languages with lots of features - Usually, the manufacturer of an embedded platform provides a C compiler. Porting a new compiler can be a LOT of work, and the resulting port can often be very buggy - Even if you can get a compiler to work, many newer languages rely on a complicated runtime/standard library, which is a deal-breaker when your complete program has to fit in a few kilobytes of ROM

amw-zero 7y ago

You’ll find that for very serious, industrial applications, a conservative mindset prevails. C may not be trendy at the moment, but it powers the computing world. Its shortcomings are also extremely well known and also statically analyzable. Also, think about when flight software started being written. Was Rust an option? And once it came out, do you expect that programmers who are responsible for millions of people’s lives to drop their decades of tested code and development practices to make what is a bet on what is still a new language? What I find interesting is this mindset. My conservativeness on a project is directly proportional to its importance / criticality, and I can’t think of anything more important or critical than software that runs on a commercial airplane. C is a small, very well understood language. Of course it gives you nothing in terms of automatic memory safety, but that is one tradeoff in the list of hundreds of other dimensions. When building “important” things it’s important to think about tradeoffs, identify your biases, and make a choice that’s best for the project and the people that the choice will affect. If you told me that the moment anyone dies as a result of my software I would have to be killed, I would make sure to use the most tried-and-true tools available to me.

AtlasBarfed 7y ago
You're advocating throwing baby out with bathwater. Rust interops with C seamlessly, doesn't it? You don't have to throw out good code to use a better language or framework. C may be statically analyzable to some degree, but if Rust's multithreading is truly provable, then new code can be Rust and of course still use the tried and true C libraries. Disclaimer: I still haven't actually learned any Rust, so my logic is CIO-level of potential ignorance.
- jschwartzi 7y ago
  The issue is that you’re trading a problem space that is very well understood for one that isn’t. Making a safe program in C is all about being explicit about resource allocation and controlling resources. So we tend to require that habit in development. It’s socialized. The only thing you’d be doing is using technology to replace the socialization. And you’d be adding new problems from Rust that don’t exist in the C world. It’s tempting in a lot of cases to read the data sheet and determine that the product is good enough. But there are a lot of engineering and organizational challenges that aren’t written in the marketing documents. Those challenges have to be searched for and social and technological tools must be developed to solve those challenges. As an exercise in use of technology it looks easy but there’s an entire human and organizational side to it that gets lost in discussions on HN.
- NextHendrix 7y ago
  Wanting to suddenly start using rust would mean putting any and all tools through a tool qualification process, which is incredibly time consuming and vastly expensive. In the field of safety critical software, fancy new languages are totally ignored for, at least partially, this reason. What's really safer, a new language that claims to be "safe" or a language with a formally verified compiler and toolchain where all of your developers have decades of experience with it and lots of library code that has been put through stringent independent verification and validation procedures, with proven track record in multiple other safety critical projects?
- prostheticvamp 7y ago
  > Disclaimer: I still haven't actually learned any Rust, so my logic is CIO-level of potential ignorance And yet you seem to write with such confidence. /Are/ you a CIO? It’s the only thing that makes sense.

bdavis__ 7y ago

Ada is used a fair amount in high $ projects. Toolchains are expensive, and the C compiler is provided for free from the chip / board vendor.

hechang1997 7y ago

Isn't Ada already used in areospace industry?