The Pragmatic Studio

Create Mix Project


Running Elixir

Here's a quick recap of the commands we used in the video to run an Elixir file:

  1. Run the elixir command with the relative path of the Elixir file:

    $ elixir lib/servy.ex

    The file gets compiled into bytecode (in memory) and then run on an Erlang virtual machine.

  2. Fire up an iex (Interactive Elixir) session and then use the c helper function to compile and run the file:

    $ iex
    iex> c "lib/servy.ex"

    The c helper function compiles the given file in memory, the module (Servy in this case) is loaded into the session, and any code outside of the module is interpreted.

    To exit the iex session, press Ctrl+C twice.

  3. Alternatively, you can tell iex to interpret an Elixir file while starting by passing the relative path of the file:

    $ iex lib/servy.ex
  4. When you start a standard iex session, it doesn't know about the paths and dependencies of a mix project. So to start a session in the context of a project, you need to pass the -S mix option:

    $ iex -S mix
  5. Finally, to recompile a module while in iex, use the r helper function:

    iex> r Servy

    This recompiles and reloads the given module, which is Servy in this case.

Exercise: Explore Helper Functions

Start an iex session and then type h (followed by Return) to see all the helper functions at your disposal. You might also want to spend a few minutes reviewing the online documentation for the IEx module.

Want to re-run something you've already typed in iex? No problem. Just hit the up arrow to step back in iex history and the down arrow to step forward.

Exercise: Enable Shell History

The iex shell can keep a history of expressions you've run so you can use up/down arrow keys to traverse the history. We love this feature! Oddly, shell history is disabled by default. To enable shell history, add the following line to your .zshrc, .bashrc or the like:

export ERL_AFLAGS="-kernel shell_history enabled"

Once you've changed the appropriate file, make sure to either open a new command-line window or source your .zshrc or .bashrc. Then fire up an iex session and you should have shell history.

Running Elixir with Sublime

If you're using Sublime Text with the elixir-tmbundle plugin as we are in the videos, you can run an Elixir file by first going to the menu item Tools -> Build System and selecting elixir. Then hit Cmd-B to run the file and see the build output as shown in the video. Hit Esc to close the build output pane.

Code So Far

The code for this video is in the mix-project directory found within the video-code directory of the code bundle.

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