dnf install erlang elixir

On OS X and MacOS, Elixir can be installed via the common package managers:

Homebrew

$ brew update
$ brew install elixir 

Macports

 $ sudo port install elixir

# Fetch and install package to setup access to the official APT repository
wget https://packages.erlang-solutions.com/erlang-solutions_1.0_all.deb
sudo dpkg -i erlang-solutions_1.0_all.deb

# Update package index
sudo apt-get update

# Install Erlang and Elixir
sudo apt-get install esl-erlang
sudo apt-get install elixir

Elixir is available in main packages repository.
Update the packages list before installing any package:

emerge --sync

This is one step installation:

emerge --ask dev-lang/elixir