Well, it's a skin on the rocket that will make it big. While they generally say that Elixir runs on top of the Erlang VM there happens to be a big fat Erlang/OTP layer in-between which Elixir and its libraries make full use of. This is just smart of course but not mentioning doesn't paint the whole picture.
I'd say Elixir is the skin, like you say: without it, all your rocket pieces are out in the open and not particularly aerodynamic, and they'll start breaking off and you won't be going to space today. There are other skins, though, like LFE and Erlang itself.
The Erlang VM is the engine. You can make a beautiful, sleek, aerodynamic rocket, but it ain't going anywhere unless you literally light a fire under its butt. It helps that BEAM helps the rocket go fast :)
Of course, you need some sort of structural piece to hold your engine and your aerodynamic skin in place, lest your rocket crumples itself up into a ball at launch. That's where OTP comes in: providing a robust structure for your rocket.
Last but not least, you need to launch it. Rebar and Mix work reasonably well as launch clamps in this really contrived metaphor. You also have exrm (or Distillery nowadays, I guess) that works as the VAB, in which your rocket is put together so it can be launched.
Except that “rockets” built with Erlang have been aerodynamic, production-ready, and deployed some 20 years before Elixir has even existed and they are still in use today. They did not start breaking off and, yes, they actually went to space, as opposed to what you imply in a very sneaky way in your first statement. If you want to be fair, you can say that Elixir is another skin of Erlang, the other way around does not hold.
That's exactly what I said, though: "There are other skins, though, like LFE and Erlang itself".
I personally consider Elixir to have fewer aerodynamic bumps and other sources of drag than Erlang itself, but that's just, like, my opinion, man. Obviously people will disagree with that, and that's fine.
Wow, rvirding! Thank you for everything. Distributed software is actually a pleasure to write thanks in large part to your the many years of work.
The rocket analogy is a good one, too. What Erlang accomplishes is massive, and Elixir uses and benefits from all of it.
I don't want to downplay what Elixir accomplishes, either ... to use a SpaceX analogy, Elixir and its ecosystem are like the guidance systems and deployable struts that let you land rockets repeatably on a barge in the middle of the ocean. It uses macros to make solving problems with rockets easier and more widespread, and maybe it also increases our ambition because of it. (I'm thinking about projects like phoenix_pubsub especially Tracker, ecto, the 1.4 registry, etc).
