Curious though, in what would you implement the examples I gave?
Of course, I am not an expert on the requirements of all those projects. Maybe some fact about functional languages makes them entirely unsuitable. If there is a technical reason why C is being used, I would like to know it; if the reason is just, "Well that's what the libraries are written in, that is what most people know, there was a bunch of legacy code, etc." then it only proves that technical reasons are easily trumped by practical concerns. Like I said earlier, it is hard to get away from the large C and C++ codebase that we have to deal with today, despite all the problems of those languages and despite the widespread availability of better languages.
And promptly blew up the rocket.
While a famous incident attributed to Ada, I can safely say that C and other popular languages have done far more damage. Even if not in terms of exploding rockets (I don't know), but time lost debugging, fiddling with checks that would be handled in other languages and so forth.
I like to tell people with Ada I can spend my time adding value rather than fighting against the language because of it's minimalism and the bugs that come with that.
The Ada way of doing things really is a whole other world with completely different goals in mind than what fanboys and fangirls (I'm using the term dismissively, but there are real problems with new languages) will tell you about the new language they're using that was thrown together last weekend. Ada, of course, is far from perfect, but the blemishes like unbounded string syntax (I hope to see that fixed next revision! Ada just had a new revision!) are not enough to put me off from all the safety and checking the language does for me.
I must tell you that it was the winner of a DoD contest to create a kind of perfect language. There was a document called the Steelman that outlined everything the DoD's perfectly readable, maintainable, reliable, safe language would look like. Three of the four entries were Pascal-derived, not C!
If there is one thing Ada will do for you, if you let it, is demolish your ego. Every stupid thing you do will be caught by the compiler and you will scorned. The compiler will piss and moan catch all sorts of fantastic errors that you'd have to pop into a debugger for in C. Some folks have this notion that they are infallible, but "to err is human", right? You're welcome to turn off the checks in specific instances or project-wide (if you're nuts), but this isn't me. I'd love to think it is—and I write pretty great Ada these days—and I still don't have the gaul to turn off compiler checks.
Everything isn't a pointer in Ada, we can nest functions. Hell we nest packages and do sorts of things that just don't translate to Java, C++ or C, but now I'm just rambling.
I think Ada is a great choice for anything more than a shell script. Learning it introduces you more to a software engineering mindset because the language is built for software engineering, not hacking something together— though, in time, you will be capable of it. It's not the change of mindset like switching from procedural to functional, but it may be just as enlightening.
Secondly, I am unable to grok functional programming, which is why I quit trying to learn Haskell. I tried, I really tried but there's no way I'm able to wrap my head around functional programming. In my mind, there's a long list with two digits in hex, that the computer iterates as fast as possible. So if Ada is a functional only language that puts the brakes right there. If no, I'd be more than happy to start learning.
In the beginning she was complaining a lot about the language's verbosity, but with the time she spent on the project she eventually became an Ada advocate! :)