Everyone thinks "Elm should compile to X" where X is a thing they like. Here is someone saying
Go is the right one. Why not go through OCaml or C# or Java or or Scala or F# or Haskell or ES6 or C++ or Rust or node.js?
I cannot stop this in general, but please stop doing it on elm-dev. It's not relevant to OP and everyone here has heard this endless iterations of this idea. The hard part of supporting a domain is not the compiler. It is making a good ecosystem. Python is nice for scientific computing because of things like NumPy and SciPy, not because of whatever backend. Elm is nice for front-end because of the ecosystem, like the HTML library and the Elm Architecture, not the particulars of code generation. Just putting a typed functional language in a domain does not mean it will be fun and productive in practice!
So say we choose to go through Erlang. Great. Now the question is "how do you write a typed server with no side-effects that is (1) true to the spirit of Elm and (2) feels nicer than other server languages?" That's the hard question. Writing a backend is like 10% of what it takes to make a project like this worthwhile. And ultimately, the ideal form of a project like this has its own bespoke backend, going to assembly more directly, like this thread was about.
Hopefully I don't sound upset. I'm not! This whole "compile to X and it's done" oversimplification is just becoming a bit of a silly meme, and the explanation of why came out with some unjustified vigor ¯\_(ツ)_/¯
P.S. two important notes from What is elm-dev for? are about (1) "if you are suggesting other people do work" and (2) "lobbying for a change in prioritization". Further talk of "compile Elm through X" should move to slack or elm-discuss.