Adding support for 'ctrl-l' and 'ctrl-d' to iex

[witte-de-with]

Precheck

This is not really a new language feature, or anything close to that, so it seems like it could be OK to propose here and not on the mailing list. Let me know if that's a bad assumption.

I see that iex supports stuff like ctrl-a and ctrl-e. Would there be interest in also supporting ctrl-l (to clear the screen, like you can do with clear() currently) and ctrl-d to exit -- both standard in many REPLs and similar terminal-based programs?

Environment

• Elixir & Erlang versions (elixir --version): 1.7.0-dev
• Operating system: macOS

[michalmuskala]

Elixir relies on the Erlang shell infrastructure to provide editing and all the other support mechanisms. The request would probably need to go upstream.

[josevalim]

As @michalmuskala said, we simply rely on the Erlang shell, so we would need to add those there.

I have actually proposed ctrl+d in the past, but that is used to disconnect from a live shell without bringing the node down, so using it to shut a node down could be very risk and they did not accept it.

Supporting ctrl+l would be a nice addition, but someone would have to make it work across OSes.

[witte-de-with]

@josevalim @michalmuskala thanks 👍

[kelvinst]

@josevalim Just had a discussion about this with a rubyist friend. Couldn't we at least put a message to use ctrl+c instead when it's not being used on a live shell?

By this I mean the use of ctrl+d, rubyist (and other languages programmers) are pretty used to do ctrl+d (ctrl+c does nothing on irb).

[kelvinst]

Also, important to notice this seems like something that is open to discussion by the erlang core team, since this https://bugs.erlang.org/browse/ERL-331 still open. Maybe we should do some noise there, IDK.

[OvermindDL1]

@kelvinst The BEAM does not expose unix signals internally, so again that would have to be proposed/PR'd into Erlang itself, not Elixir. You should ask them? :-)

[kelvinst]

@OvermindDL1 yeah, I guess I'll just ask them on the issue I mentioned above! 👍

[josevalim]

The BEAM does expose exit signals from 20.x. Check the :os module.

[OvermindDL1]

The BEAM does expose exit signals from 20.x. Check the :os module.

Oooo, really? That's awesome! There are things that I can use those for (like reloading certain configs), wonder how I missed that addition. :-)

Thanks!

[kelvinst]

Well, seems like BEAM does expose the OS signals, but not sigeof, which is what normally ctrl-d is mapped to. 😕

http://erlang.org/doc/man/os.html#set_signal-2

[sodapopcan]

Hi! I'm pretty new to Elixir and was quite missing ctrl-l (and ya, ctrl-d would be nice too).

It seems like there is nothing to be done on Elixir side of things, but I just wanted to ping this this 2+ year old, closed issue.

From explanations here, my understanding is that iex piggybacks off of Erlang's REPL. When visiting the Erlang issue linked by @kelvinst https://bugs.erlang.org/browse/ERL-331, it looks like in the Erlang REPL you can type q() to quit. Why does this not work in iex? I don't mind having to press ctrl-c twice, but it's a little jarring to always see that message.

Being told "Nope, this can't ever happen" is not a deal-breaker for using Elixir for me by any stretch! I'm merely wondering if anyone has been sitting on new insight around this in the last couple of years.

✌️