Can I use other modules from .exs files?

Suppose I created a new app with mix new app.
Then I placed a new hello.exs file to the root with this code:


When I run this with elixir hello.exs, I’m getting hello printed, followed by the error:
(UndefinedFunctionError) function App.hello/0 is undefined (module App is not available)

Is there a way a make it available?
And how can I use modules declared in other .ex / .exs files from inside an .exs file?

You could use mix run to run a script in the context of your application.

Though why do you want that? Perhaps a mix task is better suited to solve your actual problem?

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Yep, mix run hello.exs does indeed work! Thanks!
If I to want to run just one function in the app and quit, what is the best way to do it:

  • Run e.g. mix run -e App.hello
  • Create an .exs file and run e.g mix run hello.exs
  • Some other way?

If it is a one off thing, then mix run -e is probably the thing, if its something you do more often, especially if it becomes a part of your workflow, rather than just for debugging things, write a mix task that you then can run with mix your_app.your_task.


Thanks! ‘Tasks’ are OK with me. Will start using them!

Only I think the Guides on should be updated to include an article about such usage of Task. Similar to this article I have just found: