The software has apparently been written in C++, it all sounds like a bit of a farce. EDIT: to clarify the above comment, the context is the use of C++ and mainstream tools for 8 million lines of safety critical code.
C++ is unsafe by default and you have to write lots extra checks to make sure your code is bulletproof. Ada is safe by default and you have to be verbose to do powerful-but-dangerous things with pointers.
While yes, you can write secure and fault-tolerant code in any language and insecure and buggy code in any language, the sheer amount of C and C++ software that has been demonstrated to be insecure and very buggy in recent years raises some questions about whether that's the tool we want to use.
Languages are tools. C is a $5 wrench with a blade for a handle. Ada is a pocketknife where you can pull out the wrench or blade if you need it. Both of them can do the same things, but with one you have to be very, very careful to not cut yourself.
The problem wasn't programmer salary, it was that their budget was so big that they wanted to hire extra people and could not find enough Ada programmers. Yup. It got written in C++ because they wanted to spend more money and there are more experienced C++ developers than Ada developers.
Haskell doesn't even have a spec
And Haskell does actually have a spec[1], but almost everyone uses GHC extensions so I suppose that's kind of moot.
1. https://wiki.haskell.org/Language_and_library_specification
No you don't, just use RAII and you cover almost all the safety issues. Put all memory allocations, file openings, mutex locking and other resource acquisition in constructors and the matching cleanup in deconstructors and it becomes very safe. Now, not only is memory cleaned up and exception safe, but several classes of file handling and multi-threading issues are categorically fixed. There are a few other rules to enhance this to the point of preposterous safety, but with just this technique I see fewer memory leaks than I do with some garbage collected languages.
The big safety issues occur when people take the unplanned style of treating C++ as if it were C with Classes. Something that exacerbates this is a plethora of bad training material (mostly old from before C++03) and even university classes that use manual memory allocations outside a constructor (naked new statments), exceptions and manual memory releasing in exception unsafe ways.
I am sure Ada can be used incorrectly, now imagine if in an old standard not all Ada compilers supported the same language features. Imagine the subset of common features was dangerous as hell. Imagine creating a memory structure like a linked list because only some compilers provided one prewritten and some are implementations were missing core language features. However, all the compilers ship with dangerous tools to build it wrong. This was C++ in 1995, and many people who learned it then never unlearned their mistakes.
C++03 laid down a bunch of technical fixes and a minimum benchmark for decent compilers. It could have been used safely with what I described above, but much of the developer community was change averse. Now with C++11 we are changing and really cool things are happening because the developers are treating it like a different language.
I wonder if it meant "The guys who know Ada are all furiously writing F-22 software" -- parenthetical aside, the F-22 was in flight testing and development during the same years that the F-35 project was getting underway, so there would have been high demand for people experienced with developing mission critical flight software -- "and therefore we have to go with the guys we can spare, who mostly know C++ or Java or something". Or did they mean "No one coming out of school knows Ada anymore so let's go with a more widely known language"?
EDIT: But yeah, the major issue (regardless of their preference for engineers over computer scientists) is a general lack of experience in the people they hire [for the domain].