Bad news, everyone! We can longer complain about Unicode-unaware upcase/downcase in Elixir & Erlang anymore!
As of today, thanks to José Valim (project's leader), Elixir's upcase and downcase functions are using the Unicode database:
iex(1)> String.upcase "Γεια σας"
And you can obviously use this functionality in Erlang as well: https://groups.google.com/d/msg/erlang-programming/x9WcPkQJ8zE/HyL4H37ZD2UJ