Module MyMacro is not loaded and could not be found

Questions / Help
1

Hi all
I am trying to compile my exs file and I’ve got

module MyMacro is not loaded and could not be found

and do not know, what am I doing wrong.
I have two modules, the one import the another, that looks like(the filename is my_macro.exs):

defmodule MyMacro do
  defmacro example({value, _, _}) do
    IO.puts "You'll see me at compile-time: #{inspect value}"

    quote do
      IO.puts "You'll see me at run-time: #{inspect unquote(value)}"
    end
  end

end

and the other(the filename is run.exs):

defmodule Run do
  import MyMacro

  def run do
    IO.puts example(2 + 3)
  end
end

When I try to compile the run.exs file, I’ve got error:
iex(2)> c "run.exs"

== Compilation error on file run.exs ==
** (CompileError) run.exs:5: module MyMacro is not loaded and could not be found

And the file structure looks like:

Screen Shot 2016-04-10 at 22.34.10.png686×674 32.8 KB

What am I doing wrong?

1 Like
2

I don’t know what you did before compiling run.exs, but probably you missed to compile my_macro.exs, also it maybe, that you need to load the module after compiling.

NB: You are not meant to compile *.exs but *.ex. Even if this distinction is merely theorethically today, it is still an important sign for developers, if the can “run” a file or if they need to compile it.

4 Likes
3

Sorry I mean, I tried to import run.exs into shell via:

iex(1)> import_file("run.exs")
** (CompileError) iex:2: module MyMacro is not loaded and could not be found

As you can see as error, I’ve module could not be found.
What do I have to do?

4

As I said already, you need to compile the file containing MyMacro before you use its Macros in another module.

Proof:

$ ls *.ex
my_macro.ex  run.ex

$ ls *.beam
zsh: no matches found: *.beam

# my_macro.ex
defmodule MyMacro do
  defmacro example({value, _, _}) do
    IO.puts "You'll see me at compile-time: #{inspect value}"
    quote do
      IO.puts "You'll see me at run-time: #{inspect unquote(value)}"
    end
  end
end

# run.ex
defmodule Run do
  import MyMacro
  def run do
    IO.puts example(2+3)
  end
end

$ iex
Erlang/OTP 18 [erts-7.2] [source] [64-bit] [smp:4:4] [async-threads:10] [hipe] [kernel-poll:false]

Interactive Elixir (1.2.4) - press Ctrl+C to exit (type h() ENTER for help)
iex(1)> c "run.ex"

== Compilation error on file run.ex ==
** (CompileError) run.ex:2: module MyMacro is not loaded and could not be found
** (exit) shutdown: 1
    (elixir) lib/kernel/parallel_compiler.ex:202: Kernel.ParallelCompiler.handle_failure/5
    (elixir) lib/kernel/parallel_compiler.ex:185: Kernel.ParallelCompiler.wait_for_messages/8
    (elixir) lib/kernel/parallel_compiler.ex:55: Kernel.ParallelCompiler.spawn_compilers/3
       (iex) lib/iex/helpers.ex:168: IEx.Helpers.c/2
iex(1)> c "my_macro.ex"
[MyMacro]
iex(2)> c "run.ex"
You'll see me at compile-time: :+
[Run]
iex(3)> Run.run
You'll see me at run-time: :+
ok
:ok
iex(4)> 
BREAK: (a)bort (c)ontinue (p)roc info (i)nfo (l)oaded
       (v)ersion (k)ill (D)b-tables (d)istribution
^C%                                                                                                                  
$ ls *.beam
Elixir.MyMacro.beam  Elixir.Run.beam
6 Likes
5

Thanks you so much :slight_smile: