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Comment by azth | Hacker News Reader

What was the stack used to write such a system? Was it a lot of C++? And what storage systems did they use? Sounds pretty cool.

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The system as a whole used C, C++, Python, and some Java/JS-family stuff in the infrastructure backends. You can find a long tail of other languages scattered throughout the organization, like Go, Rust, Lisps, and Swift, etc. I wrote a fare-cost-calculator in Mathematica awhile ago, as an example.

As for storage systems, no idea. The stuff I know was all custom, but I was deep in the stack most of the time and don't do much with databases.

>The system as a whole used C, C++

It all makes sense now. Astounding its legal to use C/++ in a safety critical situation.

Uhh... you do realize tons of safety-critical systems in use today were written in C and C++, right? As in _most_ of them, for the past ~30 years?

Airplane systems, telecom equipment, medical equipment, satellite and space launch equipment, railway systems, etc., etc.

There's other languages used as well obviously, and even just assembly in some parts of some systems, but in terms of the majority it's C and/or C++.

Yep, I somewhat agree. The C mostly comes from Linux [1]. For the rest, "there are reasons".

[1] https://ossna2020.sched.com/event/c3QN/there-is-no-store-for...

C and C++ are used pretty extensively in the embedded world. For a lot of safety critical stuff though, typically a safer subset of those languages are used, such as MISRA C and MISRA C++, alongside static checkers and validated toolchains.

I don't know about the GNSS pipeline specifically but I used to work at Cruise, and most things at Cruise are written in C++ (although there's a smattering of Python for data/ML code that runs offboard).

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