I live near Sydney University ( not my alma-mater ). In a rather serendipitous turn, one day on my way home from the shops I was walking past one of the USYD buildings and there was a giant stack of library books that had thrown out onto the sidewalk as rubbish to be collected by the council.
It turns out they were old science faculty books that were no longer prescribed material. I started looking through them and found several books on Safety-critical software development in Ada, several books on hardware design and several others on software development. I took them all home, at first thinking the Ada ones would just be some archaic novelty. When I got a chance to read them I was amazed. I was expecting something akin to COBOL from the language. Instead I found a language that was extremely well designed for its domain. I'd already done a bit of embedded and operating system development, and I could immediately see how Ada would benefit a developer in these areas. Even representation clauses alone are such a huge convenience for low-level programming.
I haven't looked back since. I was actually in the process of preparing a bare-bones example of operating system development in Ada, if this post had been three days later I'd have been able to link the finished product here right now.
Why Ada Is the Language You Want to Be Programming Your Systems With
191–200 of 330 posts
Re: Why Ada Is the Language You Want to Be Programming Your Systems With
#192Earlier quoted context omitted.
ALGOL 60. https://en.wikipedia.org/wiki/Edsger_W._Dijkstra#Compiler_co... : ”Dijkstra was known to be a fan of ALGOL 60, and worked on the team that implemented the first compiler for that language. He was closely involved in the ALGOL 60 development, realisation and popularisation.” Also: Haskell and pascal over C++ and Java ( https://www.cs.utexas.edu/users/EWD/transcriptions/OtherDocs... )
…for CS instruction. I've never come across any indication that Dijkstra wrote actual code (in the sense of something executing on a computer) after 1970 or so. The algorithms in the EWD notes are all written in ALGOL style pseudocode. Dijkstra was the CS equivalent of the Patent Law concept of a "Non-Practicing Entity", which gave him great liberty to troll all programming languages without exposing his own choices…
If I could upvote this twice, I would.
Re: Why Ada Is the Language You Want to Be Programming Your Systems With
#193This article promotes a popular misconception of the programming situation for defense projects in the 1970s. There may have been "hundreds of specialized programming languages" in existence that could be used, but just a handful actually predominated. Most aeronautical projects were done in JOVIAL. I've talked about this history with engineers from the 1960s-70s. They did not regard the introduction of Ada as a good…
I'm sure that's all true. There is something to be said for a language that was written to a spec from the beginning, however. That is a luxury that few languages today can claim; most language specs were written after the first version(s) of the language were implemented, and were written to match the implementation, not the other way around. Writing the specification first makes for a much cleaner language, though…
Languages are tools to codify behaviors. The fact that we spend so much time debating which tool is better instead of “building bridges”, is why I left this industry.
Just look at the web front end. Absolute cluster fuck.
Re: Why Ada Is the Language You Want to Be Programming Your Systems With
#194First, this is a great introduction article to Ada. It's a great history lesson, and analysis of where it's used and why. That said, it seems to be arguing for something in a vacuum. Where is the mention of other new programming languages that also fit this category? Where is the mention of Rust? Rust fits all the same requirements: - A general, flexible design that adapts to satisfy the needs of embedded computer ap…
Might as well mention F* then! > F* (pronounced F star) is a general-purpose functional programming language with effects aimed at program verification. It puts together the automation of an SMT-backed deductive verification tool with the expressive power of a proof assistant based on dependent types. After verification, F* programs can be extracted to efficient OCaml, F#, C, WASM, or ASM code. This enables verifying…
And the "worst name" prize goes to ...
Re: Why Ada Is the Language You Want to Be Programming Your Systems With
#195Earlier quoted context omitted.
There's always someone who brings this up whenever Ada is mentioned, as if it serves as a damning refutation of Ada's reputation as a safe language. That bug was caused by a series of design failures if anything, rather than software bugs. From memory, they reused the inertial reference system from the Ariane 4 mission without testing its suitability for a different delivery vehicle. The actual 'bug' was caused by an…
>> he actual 'bug' was caused by an integer overflow occurring due to the velocity variable not being wide enough to handle the higher horizontal velocities of the newer rocket. Something all that fancy type system should have prevented. I found it interesting in the Hackaday piece that the C code xample called out the size of an integer while the Ada version did not. The Ada version caught an implicit conversion, bu…
Ada is miles ahead of Rust when it comes to C interoperability. I posted this before in one of the other Rust threads, but you can't get more than two paragraphs through the official Rust FFI documentation ( https://doc.rust-lang.org/nomicon/ffi.html ) before being asked to install a third-party dependency. The 'Interfaces.C' package is defined in the Ada language specification. And, as others have mentioned, Ada's language defined pragma directives, or Ada2012's aspects provide a way to implement FFI.
Re: Why Ada Is the Language You Want to Be Programming Your Systems With
#196Earlier quoted context omitted.
The software in the case of the 737 max performed exactly according to the spec. The problem is that the spec was buggy. The language can't fix a buggy spec. Note that the bug which caused the Ariane V disaster was written in Ada. And that was caused by the language. If the Ariane V code was written in C and the value simply overflowed, nothing negative would have happened. (The value would be hilariously wrong, but…
> "If the Ariane V code was written in C and the value simply overflowed, nothing negative would have happened" So... what you're saying is that the language not recognising an exception conditional has occurred is a better outcome in mission critical applications? "wasn't necessary", "It was an oversight", "Which was uncaught"... With these phrases you've already pointed out that the developers had improperly implem…
There is something to be said for not just halting on an error in production systems. Its the same reason assertions are usually turned off on production builds.
Yes ideally the programmers should have handled the exception, but once your in production and the system is running, should you really just halt the whole program due to an exception the prograera didn't foresee?
Re: Why Ada Is the Language You Want to Be Programming Your Systems With
#197Earlier quoted context omitted.
We came to the same conclusion at Kubos, and moved from C to Rust for most of our flight segment/application code (embedded Linux on the satellite OBC). https://www.kubos.com/
Awesome, do you think it’s a hard sell for old school government contractors? I am passionate to write embedded systems with Rust, but I worry it will be too hard of sale to d school contractors with stacks already written C, and C developers on staff.
I've had a good number of conversations actually with some NASA FSW coders, and in general they're open to these ideas. NASA has a project with architectural and structural goals pretty well-aligned with what we set out to do at Kubos: https://cfs.gsfc.nasa.gov/Features.html
The biggest challenge is to prove that it works. The space software community historically is very conservative and risk-averse, and mostly for good reason. As Kubos (and hopefully others) get more flight heritage with Rust on the flight segment, it'll be a much easier sell.
That's the biggest obstacle I think. Someone will have to break the seal and establish that "Rust in Space" actually succeeds consistently, then larger "trad space" organizations will follow.
Re: Why Ada Is the Language You Want to Be Programming Your Systems With
#198Earlier quoted context omitted.
> "If the Ariane V code was written in C and the value simply overflowed, nothing negative would have happened" So... what you're saying is that the language not recognising an exception conditional has occurred is a better outcome in mission critical applications? "wasn't necessary", "It was an oversight", "Which was uncaught"... With these phrases you've already pointed out that the developers had improperly implem…
There is something to be said for not just halting on an error in production systems. Its the same reason assertions are usually turned off on production builds. Yes ideally the programmers should have handled the exception, but once your in production and the system is running, should you really just halt the whole program due to an exception the prograera didn't foresee?
For mission-critical software like avionics or a nuclear power plant? Absolutely! At design time you better figure out what all the error cases are, and blindly steamrolling over them when they should be triggered makes a bad problem worse (e.g. look at Cloudbleed where unchecked out-of-bounds reads starts disclosing other people's banking information).
Assertions are also usually turned off for performance reasons, not to allow the program to plow through invariants being violated.
Re: Why Ada Is the Language You Want to Be Programming Your Systems With
#199Earlier quoted context omitted.
Wasn't the ill fated code itself written in Ada? That is essentially all that goes on boeing aircraft. I don't think a lack of software engineering rigor is to blame for the design mistake.
Possibly; I don't work for Boeing or their subcontractor. But I was getting at more of the general sense that as aircraft become more and more computerized we need more rigour and standardization of the sort that gave rise to Ada, and less of the aerospace equivalent of hacking things together in perl.
While I understand the instinct, there is a flip side. A while back Lutz Prechelt posed the phonecode problem, inviting solutions in multiple languages. While he didn't specify error handling, the Perl solutions were on average better at error handling than the compiled language solutions.
Re: Why Ada Is the Language You Want to Be Programming Your Systems With
#200Flashbacks to Prof. Feldman's classes
Or Dr. McCormick's classes. CS 101 with Ada. Students 2 years behind me got to learn Java or Python.
He wrote 3 books on Ada. http://www.cs.uni.edu/~mccormic/