gistfile1.txt

%% посмотреть во что компилится макрос

iex(14)> defmodule T do                                                                                                                                                               
...(14)> def f(fun, arg), do: apply(String, :"#{fun}", [arg])                                                                                                                         
...(14)> end |> elem(2) |> :beam_lib.chunks([:abstract_code]) |> elem(1) |> elem(1) |> get_in([:abstract_code]) |> elem(1) |> :erl_syntax.form_list |> :erl_prettypr.format |> IO.puts
warning: redefining module T (current version defined in memory)
  iex:14

-file("iex", 14).

-module('Elixir.T').

-compile(no_auto_import).

-export(['__info__'/1, f/2]).

-spec '__info__'(attributes | compile | functions |
                 macros | md5 | module | deprecated) -> any().

'__info__'(module) -> 'Elixir.T';
'__info__'(functions) -> [{f, 2}];
'__info__'(macros) -> [];
'__info__'(attributes) ->
    erlang:get_module_info('Elixir.T', attributes);
'__info__'(compile) ->
    erlang:get_module_info('Elixir.T', compile);
'__info__'(md5) ->
    erlang:get_module_info('Elixir.T', md5);
'__info__'(deprecated) -> [].

f(Vfun@1, Varg@1) ->
    erlang:apply('Elixir.String',
                 erlang:binary_to_atom(<<case Vfun@1 of
                                           Vrewrite@1
                                               when
                                                 erlang:is_binary(Vrewrite@1) ->
                                               Vrewrite@1;
                                           Vrewrite@1 ->
                                               'Elixir.String.Chars':to_string(Vrewrite@1)
                                         end/binary>>,
                                       utf8),
                 [Varg@1]).