interrupting the repl

[seebs]

If you are a newbie to clojure, it's easy to accidentally write something that becomes an infinite loop. If you try to evaluate it in the repl... Now what? Some REPLs apparently allow ^C to interrupt an evaluation, without killing the entire REPL process and losing its context. I can't tell whether Calva does, but if it does, I couldn't find out how by looking in the documentation.

It feels to me like "how do I stop this" should be prominent in the documentation, we've been having problems with runaway processes since Fantasia. :)

[PEZ]

Thanks for pointing this out, @seebs! You are very welcome to have a look at the documentation and REPL Ux, and file PRs addressing this.

Some things to consider for you (or anyone taking it on):

• There indeed is a way to interrupt runaway evaluations. The VS Code command: Calva: Interrupt Running Evaluations. It's default bindings are ctrl+alt+c ctrl+alt+d (so you can hold ctrl+alt/option while pressing c, then d).
• ctrl+c isn't really free, as it is used for Copy on Windows and Linux. Also, as a user you might think it kills the REPL. (Which it does if you use Jack-in and press ctrl+c in the Jack-in terminal.)
• Information about how to interrupt evaluations could be added to the REPL greetings.
• The REPL statusbar item brings up a menu. This menu could be a place to discover this command.

Cheers!

[seebs]

Thanks! I did in fact look in the docs for "interrupt" a bit, but apparently I did not look in them enough.

[PEZ]

I don't think it is mentioned in the docs. You should have searched the command palette instead. 😄

[seebs]

Huh. I do "calva: inte" in the command palette and don't get any matches. Calva claims to be version v2.0.331, if that matters.

[PEZ]

I'm guessing you haven't connected a REPL. Otherwise we might have a bug.

[seebs]

! Right you are. I suspect I broke it, sent a SIGINT to the process because someone said ^C had worked in something else so I thought "oh, maybe it traps sigint", then searched the palette for "interrupt", didn't find it, restarted the repl...

[bpringe]

@PEZ Might the interrupt command be a good thing to include in the Getting Started REPL? It could include some code that when evaluated, doesn't terminate, and then instruct the user to run the interrupt command.

[PEZ]

@bpringe Indeed!