No they are not competitors at all - Elm is front end and Elixir is backend. Elm is a HTML/CSS/JS transpilier, I can’t see why they would want it on the server as well, and even if they did, it would be JS - nobody in their right mind would want JS on the server

Here’s Joe Armstrong’s research on GUI options for Erlang: http://erlang.org/pipermail/erlang-questions/2017-July/092949.html

Kind of late to the party here, but for anyone still interested in this, I’m currently building a phoenix app that I plan to distribute on desktops using webview, seems to be the most simple and straightforward approach.

For GUIs in Elixir you can still use Erlangs wx-module. For this to work, of course, it is necessary that your Erlang release is compiled with wx included.

But for the client side I’d prefer a more lightweight solution that does not pull in a full gigabyte as runtime dependency…

This in mind, I do think, currently the best approach is a JavaScript-application which runs in the Browser and is written in a way that it can work without internet access. This could even update itself silently whenever necessary (and online). Also there are multiple tools available, that can convert HTML5/JS-Applications into native applications for iOS, Android or Win mobile. They might need additional tweaking of the source though.

But if you really want to use the same language in the complete applications stack, I heard about a language called haxe which promisses exactly that, but I never tried more than a hello-world, because I#ve no project which could make use of it.

if this is your goal, Elixir is not at all well suited to learn by creating GUIs. All the answers you got above are about actually creating the GUI itself in another language (Elm, JS/HTML/CSS with Electron, Java) not in Elixir. All the above answers are good, but if your stated goal is to learn Elixir by doing GUI programming (non-web), you won’t find much/anything to support that in Elixir itself.