[nostrademons]

I wasn't thinking specifically of ML-family languages, though they could be included.

Rather, if you are in a problem domain like web-development or server-side microservices where a GC is fine, there are lots of decent options for programming languages. Python, Ruby, or PHP. Go. Any of the JVM languages - Java, Scala, Clojure, Kotlin. Swift or Objective-C. dot-NET. Many of these have had continuous attention over the last twenty years, they've got major corporate backers, and so a lot of the recent research in PL theory gets ported over to them.

If you are in a problem domain where you can't use GC - like computer graphics, games, databases, information retrieval, operating systems, or embedded - you have basically one option. C++. C++ has gotten a much-welcome facelift recently with C++11/14/17, but the core of the language is still 40 years old, and the language as a whole makes serious compromises (like memory safety) for backwards-compatibility. The excitement about Rust largely stems from its competition being C++; if you pit Rust against say Python or ES6 in the domains in which the latter are used, it's very much "Why would I use this?"