Sure, devops tools are usually more fundamental, whereas high level languages are used for things closer to the business. Twitter's backend for example is mainly powered by Scala, but you probably don't know about it, because it is not as visible to you.

Enumeration isn’t a compelling way to indicate relative frequency (in this case, frequency of usage of Go and Scala, respectively). An enumeration of size=1 is even less convincing.

That was not my intention. The example was supposed to show that not all software has the same visibility to software-developers.

> Meanwhile, as a non Java programmer, I've never seen a Scala app.

One widely known Scala application is Kafka. Some parts of it are in Java, but actual core is still mainly Scala afaik.

Yep, Kafka is probably the most popular one. I've heard that the team is looking forward to replace the remaining Scala code in the project with Java once pattern matching and co. land. Spark is another beast that was written in Scala. Many are reporting a high cost for compatibility. Nowadays, Scala community is all about Typelevel and ZIO, if you are not a category theory minded person, then you will have a hard time picking it up.

Zio's library is not based on category theory. In fact, its trying to be the opposite.

> I know about R, but nothing on my PC is written in it.

You could say the same thing about excel macros. They are both tools for wrangling data, tools that will typically not be distributed to end users.