I was following an identicon generation tutorial using Elixir.

The project was a bit older and used egd as if it was available by default in the project.

$ rebar3 compile

I discovered egd is not part of the standard library anymore. One needs to install it separately in Elixir.

Step 1: Refresh rebar

mix local.rebar --force

Step 2: Add egd to the dependencies

defp deps do
  [
    {:egd, github: "erlang/egd"}
    # ...
  ]
end

Step 3: Install dependencies

mix deps.get

I hope that helps.