One of the big differences between Erlang and Elixir is indeed that Elixir allows you to write macros in the language itself, using quote / unquote constructs j

One of the big differences between Erlang and Elixir is indeed that Elixir allows you to write macros in the language itself, using quote / unquote constructs just like lisps. This makes it easy to generate code on compile time, which is then executed in runtime without any performance penalty. A large part of Elixir itself is actually implemented as macros. For instance, the "unless" construct: defmacro unless(condition, do: do_clause, else: else_clause) do quote do if(unquote(condition), do: unquote(else_clause), else: unquote(do_clause)) end end (code simplified for clarity)