Comment by simoncion

Right. The author barely touched on the capabilities of Erlang/OTP. That section was pretty much a demo of the syntax and an advertisement of the fact that the language syntax and runtime system makes it trivial to have a distributed program that runs on separate machines.

If the author actually talked about the capabilities of Erlang, they would -at minimum- answer the questions that you'd raised, that the return value of both 'ping/1' and 'pong/0' are irrelevant because they are ignored, and that the range of 'ping/1' is not only infinite, it can accept any type for which it's legal to '+ 1'. [0] They would have also mentioned why they call 'ping' and 'pong' at the end of the respective function, the reason for which is kinda strange if you're coming from a more-normal language.

One can add annotations to functions that indicate what their input and output types are, and if you do a little bit of work, you can also indicate valid ranges/values for those types. These annotations are not checked at runtime, but can be checked by tools such as dialyzer. But, because this blog post barely even touched on Erlang/OTP's capabilities, none of that was mentioned.

[0] I think the valid types are only integers and floats, but definitely don't bet your career on that information.