[grzm]

It's much more common than just Elixir programmers. It's a common concept in computer science, particularly in functional programming or languages which permit function overloading on arguments.

https://en.wikipedia.org/wiki/Arity

Edit to add: I've heard and used arity for at least 10 years, in particular in the Clojure community. I've heard of Elixir and understand it shares some common ideas with Clojure and Ruby, but never been a part of its community.

[hopia]

In functional programming classes at the uni you probably wouldn't hear this because if they teach Haskell which I assume most do, every function always takes just one argument. That's because functions are curried by default.

I personally haven't really heard this mentioned anywhere outside of the Erlang/Elixir sphere.

[cthalupa]

This thread really surprised me - I learned about arity when learning about ternary operators, which are pretty universal - you can find ?: in all sorts of languages. I think I was learning about C when I first got a detailed explanation on the subject.

[pmarreck]

Even if every function is curried by default (and "currying" is yet another concept that may be alien to users of some languages), it is probably still useful to know with what number of arguments a function can evaluate to a value that is not just another function