Welcome to the forum Anton!
I have to ask… are you using Elixir at WhatsApp at all? 
Also in case you find it of interest, there’s also Gleam, a statically typed language for the Erlang VM (perhaps its creator, @lpil, could help in some way) and I believe @josevalim also mentioned the Elixir core team were investigating static typing. There are also a lot of threads here about static typing that you might find interesting:
Please keep us updated on how you get on and if you’d like more involvement from the community here please don’t hesitate to start some threads 
