[jon-wood]

Apparently they use "JVM languages", JavaScript, Python, Go, Lisp and Erlang in production.

I may be in the minority, but that would drive me mad. I assume they're not routinely jumping between those stacks multiple times a day, but even so is there really that much benefit that it's worth keeping track of how to do things in that many different environments?

[Homunculiheaded]

I think SICP states it best:

"In our study of program design, we have seen that expert programmers control the complexity of their designs with the same general techniques used by designers of all complex systems. They combine primitive elements to form compound objects, they abstract compound objects to form higher-level building blocks, and they preserve modularity by adopting appropriate large-scale views of system structure. In illustrating these techniques, we have used Lisp as a language for describing processes and for constructing computational data objects and processes to model complex phenomena in the real world. However, as we confront increasingly complex problems, we will find that Lisp, or indeed any fixed programming language, is not sufficient for our needs. We must constantly turn to new languages in order to express our ideas more effectively."

At a certain level of software design tying together different programming languages that are each the right tool for their job becomes just another type of programming. I currently do data science work, but even then in a given week I typically use R, Python, Lua and Java (and often Scheme in the evenings for fun). Trying to make any one of those languages do something the other is much better at is a phenomenal waste of time.

On the system level, once prototyping ends, if there's something that Java does phenomenally better than R, but we need both, that implies that you have two parts of the system different enough that they shouldn't be tightly coupled anyway. If you write a deep learning algorithm in Lua, but want to do some statisitical analysis on the results of that in R, it's good to force these things to be separated because if in 5 years you find a better model for the Lua part (maybe some better algorithm in Julia) you want to be able to swap it out anyway.

[davelnewton]

While a Single Language to Rule Them All would be cool, I ultimately prefer using the "best" language for the job based on specific requirements.

The "best" might change over time, too.

It can be a headache to manage massively-polyglot environments. At the same time, it's also pretty great for a variety of reasons. I mean, we regularly use different data stores, messaging solutions, frameworks, etc. and I don't see why languages shouldn't also be up for shuffling.

[aikah]

> I ultimately prefer using the "best" language for the job based on specific requirements.

Most shops don't think like that. Using too many languages often quickly becomes unmanageable.

I wouldn't use 6 different languages into the same project UNLESS they are part of different server/cli tools that work in isolation. I don't need to have a deep understanding of Go to use Docker, I don't need to be a PHP expert to deploy Drupal or Wordpress , I don't need to know Ruby to use vagrant,nor Java to use Cassandra. So using these tools in isolation is fine inside the same project.

[vseloved]

As for me, adaptability is one of the important traits of a senior engineer. Surely, you don't have to be an expert in every platform, but you also shouldn't go mad if you need to do some work outside of your comfort zone occasionally. Besides, every language has its strong and weak points: if you're putting arbitrary limits here, you're just limiting what you can do and the people you're going to get in a team. At Grammarly, we always erred on the side of more freedom and it worked not so bad for us so far. Although, there are different companies, each with a unique story...

[bsder]

To me: Javascript, Python, and Go aren't all that different.

You must know Javascript in this day and age given it's de facto presence on the web.

Python is my go to language, especially for mathematical analysis. I can do everything in Python that I used to need Matlab for. From my point of view, pick your favorite modern scripting language and run, the differences really are the libraries, not the languages.

I have used Go, but Go just doesn't do it for me. It doesn't offer me anything I can't get, better, in another language especially if I can choose among Python (smaller headspace), Erlang (way better concurrency) or Lisp (way better abtraction power).

Erlang is my go to language for concurrency. Once I architect it in Erlang, I probably understand the problem.

Lisp is useful when my problem requires powerful abstraction. Otherwise, it gets in the way because people can't resist using that power. Clojure has changed my opinion on this quite a bit, but I don't yet have a big project that fits in it's space quite yet.

[rcarmo]

I suggest you look at http://lfe.io - it's an interesting take on LISP...

[jessaustin]

Since "proper service encapsulation" is mentioned, it may be that each team uses whatever they like, and as long as your component speaks http you don't have to look at what other components are doing.

[krvss]

This is exactly how it is (except sometimes it is not HTTP but message queuing etc)

[jon-wood]

That makes sense, having spent the last five years on a development team that has only recently grown to four people I can forget that not every team needs all their developers to be able to work on any project!