2) Yes, interoperability is there and, just like you can use Scala libraries from Java, you just need the Elixir runtime in your path.

3) My favorite is from the String.Unicode module:

    defmodule String.Unicode do
      # ...

      def upcase(""), do: ""

      lc { codepoint, upper, _lower, _title } inlist codes, upper && upper != codepoint do
        def upcase(unquote(codepoint) <> rest) do
          unquote(upper) <> upcase(rest)
        end
      end

      def upcase(<< char, rest :: binary >>) do
        << char >> <> upcase(rest)
      end

      # ...
    end