Ideas for choosing your next language foray
My relationship with programming languages is sometimes problematic. You see, it's quite easy for me to see that the grass must clearly be greener on the other side of the language fence. Thus, I spend a lot of time doing anything from a light tinker to a full-blown deep dive into new or interesting languages.
I'm a programming language aficionado. More often than not, a dilettante.
That confessional aside, I do have guidelines that help me decide when to read over language docs looking for interesting ideas, when to tinker with it if I get "the urge", and when to do a full-blown weekend dive into a language.
WARNING this is for personal use only. Almost none of these guidelines hold water when it comes time to decide to deploy software to production.
My favorite reason to dive into a language is the creator has a very good taste in solving problems with computers or thinking about how developers think about writing programs. Though they sit on very different points in the language spectrum, Rich Hickey's (Clojure) and Martin Odersky's (Scala) both have very compelling ideas about how to design a programming language for developers such that it magnifies a developer's ability to think about solving problems with computers. Other times, the intrigue of a language designer's philosophy and work make it worth looking into a language even if I never intend to use it. I checked out Rasmus Andersson's Move solely on the strength of the rest of his work.
Languages with challenging, satisfying, or interesting principles are a source of intrigue. Haskell's principles of extremely pure functional programming and type safety are a real puzzle if you're coming from Ruby, which allows all manners of things Haskell outright forbids. Clojure's principles, taken as a whole, can be very satisfying: write small functions passing immutable data structures, with very explicit handling of program state to compose programs that eschew complexity in favor of simplicity due to boundaries. Erlang's emergent qualities are very interesting: use functions, pattern matching, and actors to implement reliable distributed systems. I saw a language that was all about making unit conversion, e.g. feet to meters, explicit in the language. Point is, some languages are fun playing around with simply to bend your brain in weird ways.
Languages that make previously inaccessible application domains simple can be a real ego boost. Right now, Swift is attracting a lot of eyeballs as it makes developing for Apple devices far simpler than it has been in the past. In the same way, Clojure makes Lisp a little easier, Erlang makes distributed systems a slightly less enigmatic, and Go makes systems programming less intimidating.
A language with a healthy culture is worth its weight in gold. If the values of the people and code in a language don't align well, you'll have a bad time. If they fit well within your own, you're going to have a ton of fun. This is the most subjective of all parameters. I find the principles around Go and Clojure really intriguing and thus find them really interesting. I'm less jazzed about Scala or C++, so I "read into them" a lot less often.
Finally, not every language is cut out for an enthusiastic tinker. I'm likely to skip languages that are highly experimental, highly mathematical, come from boring vendors, or are too similar to languages I already know or use. That crosses languages like Seph, Agda, or Python off my list.
There's half a dozen ideas to give yourself permission and treat yourself to learning a new language. Of course, the old standby excuses are pretty good too. Learning any new programming language expands your brain. Every language you learn gives you more vocabulary to solve problems, no matter what languages you use on a day-to-day basis.
Teaching yourself a new language is a winning proposition, you only have to decide where to start. And then learn the language. But sometimes the decision is harder than the learning!
Hopefully my guidelines, and perhaps some of the languages that satisfy them, will help you next time you get that itch to explore a new programming language.