Writing for correctness in a language with no memory-safety, weak type system and, till not very long ago, no standardized memory-model, and UB in every other paragraph of the specs? Good joke. If they are really doing this, they have no idea what they are doing. There are plenty of languages better for safety-critical systems than C++; even widely hated, boring Java is much better.

It's a bit off topic, but I'm being descriptive (based on professional experience) and not normative when I say C++ (and C and Ada) are used for safety-critical software. Javascript and functional languages certainly aren't.

The vagaries of the standard aren't issues since safety critical software is validated on a per-platform and per-compiler basis. Memory safety is certainly a concern during the development process but more importantly (!) GC languages (like javascript and Scala) do not have provably (for some value of provably) deterministic execution times. Determinism is also a problem for lazy languages (like Haskell).

I say that to say the zero-cost abstractions of C++ is a huge benefit when writing safety-critical software. The level of control over emitted binaries is essential and fairly rare in programming languages.

> If they are really doing this, they have no idea what they are doing.

Well, I can't speak for entire industries, but that's a pretty sweeping generalization. You might be surprised what the challenges are when writing safety-critical systems software. That being said, I'm sure large portions of the industry are ripe for innovation.

> GC languages (like javascript and Scala) do not have provably (for some value of provably) deterministic execution times

This is not unique to GC languages, but any languages with dynamic memory management. C++ new/free and STL abstractions built on top are not provably deterministic either. And if you program without ever touching dynamic memory (statically allocating and pooling everything) then GC is not a concern.

> I say that to say the zero-cost abstractions of C++ is a huge benefit when writing safety-critical software.

You're talking about performance now, not correctness. All those benefits get lost once translated to JS.

That was going to be my response..

I was replying to the statement: "For example, people also write C++ when correctness is critical". And I say if someone writes C++ in a correctness critical system, he must not know what he is doing. Even if you're using only STL, RAII and following all the good coding practices, there are still so many ways to screw things up, that C++ is among the worst choices in this regard.

Nasa and military don't know what they're doing? C++ is the go to language in mission critical systems.

NASA and military are using a whole lot of different technologies and languages, including, but not limited to assembly, C, C++, ADA, Haskell, Coq, Python and Java. Saying they use C++ for correctness, when they are using Coq or Haskell as well, is again - exaggeration. I believe they use C/C++ more for performance / low memory overhead rather than its correctness related features.