>> I don't know Ada well personally
>> But I'm not very educated.
If you don't know, please don't speculate.
I use Ada professionally and I am experimenting with Rust. Rust has great promise and I am interested to see where it will go, especially as an alternative to C++.
>> it's a bit less advanced than Rust at static checks
Ada 2012 has comparable and in many cases more advanced static checks than Rust with the exception of memory management. This is especially true of the Ada type system (https://learn.adacore.com/courses/intro-to-ada/chapters/stro...) and design by contracts (https://learn.adacore.com/courses/intro-to-ada/chapters/cont...).
If you use the SPARK subset of Ada, you can use advanced tools to prove the correctness of your program. See https://learn.adacore.com/courses/intro-to-spark/index.html
Rust's borrow checker approach to memory management is novel and SPARK is acutally adding similar concepts to the next version of SPARK (https://blog.adacore.com/using-pointers-in-spark).
>> a good bit simpler than Rust and Swift but more complex than Go
Ada is a large and fairly complex language because it was designed for hard real-time, safety-critical, embedded systems and it has been in real-world use for 40+ years. I don't think it is that simple, but judging simplicity is subjective: what one person sees as complex, another person might see as simple. You can browse the Ada 2012 Language Reference Manual and see what you think: http://ada-auth.org/standards/12rm/html/RM-TOC.html
>> a little bit old-fashioned in approach (verbose syntax and all that).
This comes from the Ada design philosophy to be explicit in everything and to prefer the use of keywords over symbols.
"Readability is more important than conciseness. Syntactically this shows through the fact that keywords are preferred to symbols, that no keyword is an abbreviation, etc." (See https://learn.adacore.com/courses/intro-to-ada/chapters/intr...)
Long-life programs tend to be read more than they are written. The Ada way is to make programs easier to read rather than faster to write.
>> I would say that Ada and Rust probably compete on some things, but given the history of Ada in industry, it's probably only in fields that already use Ada (aerospace and what-not).
This is largely true. Ada occupies a niche for aerospace and other safety-critical areas, but has not been widely adopted due to the "uncoolness" factor and the cost of most of the available Ada compilers and toolchains.
I think the popularity of Rust has peaked some interest in Ada as well, but I am not sure if it will cause any change it where either are used.
I would like to see Rust to continue to mature and get adopted for wide-spread use with multiple implementations and a language standard. As it currently stands, many aerospace and safety-critical spaces would not be willing / able to adopt Rust without a language standard and certifications. Here's hoping . . .