I think one big stumbling block people had in adopting ADA (along with there not being a good open source toolchain for a long while as noted here) is that it just looks different to people that primarily use C and similar languages, and that puts some people off.
That's sad, and I would rather it not be true, but it's become increasingly obvious to me from how people treat numerous newer languages I've seen pop up over the years.
I'd be more than willing to give Ada a chance, but when I looked at code samples I definitely had to fight an automatic response of thinking it was something out of date based on how it looks.
It's not that there aren't successful languages and have a different look and feel, it's that there's pushback against them when they are targeted towards the niches C and C++ are already strong in. Obviously many languages exist and many have become popular, but certain niches are more resistant than others and sometimes it's for non-rational reasons.
> I'd be more than willing to give Ada a chance, but when I looked at code samples I definitely had to fight an automatic response of thinking it was something out of date based on how it looks.
That's part, but not all, of what I'm talking about. The style C follows is damn old itself, sometimes predating the languages you're thinking of as out of date.
Maybe also, but not only. In contrast to Rust, Ada docs have been awful, and as long as you didn't get a commercial toolchain you had to play with some gimped version (and the really free version didn't come out until the language was 20+ years old), the build system was as “good” as C, people complain that Rust is verbose, but Ada was still a notch over, the memory model of Ada is a mere reflect of Rust's one, and (maybe I'm being subjective here) Rust's stdlib and philosophy is leagues over Ada's (Option, Iterator, closures, Result, ...).
Ada had the potential to be a Rust 30 years before, but it was never the goal of its owners.
That kind of thing happens; we're in a profession that is made up out of people.
Ada may be a good language, and GNAT may be a fine Free and Open Source Ada compiler, but Ada isn't a new programming language. Software developers only chase shiny new things. Ada is held back by its beginnings as a niche language with expensive compilers, it doesn't matter that this hasn't been the case for decades now.