How Can We Clear the Screen in Iex on Windows

Question

Please how can we clear the screen in Iex on Windows

Documented method in Iex help does not work:

• clear/0 — clears the screen

This StackOverflow Answer also does not work in Windows.

Answer 1

I've discovered it's possible, because native terminal in Windows 10 supports ANSI colors and escape sequences. The only thing is to enabled this in iex shell.

According to https://github.com/elixir-lang/elixir/blob/master/lib/elixir/lib/io/ansi.ex#L41 this option is configurable. As a quick solution just type in your iex session following code:

Application.put_env(:elixir, :ansi_enabled, true)

In order to make it permanent, you can configure iex shell in ~/.iex.exs file (https://hexdocs.pm/iex/IEx.html#module-configuring-the-shell). Just paste following into the file:

IEx.configure [colors: [enabled: true]]

Answer 2

Your best option (if this is a real problem for you rather than an annoyance) is to use an alternate Windows shell that supports ANSI Escape Sequences. See this S O question for why you can't simply use ANSI Escape sequences in a Windows Cmd Shell. One command shell alternative that does support ANSI is ConEmu. Configuring ConEmu on your machine is left as an exercise for the reader.

Answer 3

Yes, we can't clear it on Windows as far as I know. If there is one escape that we can output to the IO device to clear screens on Windows, I would love to know and add this functionality to Windows too. :)

Answer 4

Add the following to ~/.iex.exs in your home directory -- If the file doesn't exist, create it and add the following.

Application.put_env(:elixir, :ansi_enabled, true)

Edit: Note that you'll need a term that supports this, ConEmu, Cmder, etc..

Answer 5

You can use ANSI codes directly in iex on Windows with consoles that support them (like ConEmu or Windows 10 console.)

This will clear the screen in iex:

iex> IO.write "\e[H\e[J"; IEx.dont_display_result

Explanation:

• IO.write outputs to the console without a newline
• \e[ is the prefix for ANSI CSI codes
• H is the CSI CUP – Cursor Position code with no arguments, by default moves cursor to row 1, column 1
• J is the CSI ED – Erase Display code with no arguments, by default clears the screen from the current cursor position
• IEx.dont_display_result prevents the :ok result of IO.write from displaying after the screen is cleared

You can also clear the screen using IO.ANSI rather than raw escape codes:

iex> IO.write [IO.ANSI.home, IO.ANSI.clear]; IEx.dont_display_result

This is basically how clear/1 is implemented.