Smart mode prevents deleting whitespace if parentheses would change

[andreyorst]

This is a minor inconvenience. Here's an example.

Imagine you've written the let block, and you've just finished writing the expression:

(let ((first-binfing (some-expression with args)|)))

(| represents the point)

Now you want to add second binding. You press enter, and Emacs sets the indentation for you:

Oops. You've forgot to escape the binding list, and Emacs thinks that you want to add another form to first binding list. So naturally you simply delete the whitespace with backspace:

Uh oh. Parinfer smart mode prevents me from escaping the block. Deleting with backspace doesn't work anymore.

Now I have to press left arrow or C-b:

And now you finally can type (:

Other parinfer implementations allow deleting and escaping current block. Im not sure if this is a Parinfer rust thing or in your Elisp code.

Again this is not a serious issue, but rather a minor inconvenience.

[justinbarclay]

Sorry for the delay, gmail decided to put my github notifications into spam 🤷‍♀️.

This is mostly linked to parinfer-rust because it can reposition the cursor. I also verified that this behavior is part of the parinfer spec. With this demo set to smart mode it exhibits the same behavior as you've described.

However, I have checked out atom-parinfer and it does follow the behavior you've described.

I think this could be a worthy enhancement

[andreyorst]

I guess this function, when bound to "<backspace>" solves this just fine:

(defun backspace-or-delete-indentation ()
  (interactive)
  (let ((old (point))
        (new (save-excursion
               (back-to-indentation)
               (point))))
    (if (eq old new)
        (delete-indentation)
      (delete-backward-char 1))))

Do you think if your plugin should bind it by default?

EDIT: Ugh, after thinking a bit more, it will not allow to move blocks to top level, so

[justinbarclay]

Hmm from looking at other packages like parinfer for vscode, it seems they set an argument, force-balance, to true when calling into parinfer-rust. One that I never implemented when I was working on the interface for the rust plugin. This is something I plan to work on over my Christmas holiday.

Thanks for continuing to think about this problem and I am sorry I haven't been able to put more time into fixing it.

[andreyorst]

Thanks for continuing to think about this problem and I am sorry I haven't been able to put more time into fixing it.

No worries! I'm currently not using Parinfer as of this moment, mostly because of https://github.com/eraserhd/parinfer-rust/issues/92 -- at work it generates a lot of noise in merge requests or requires me to do a lot of cleanup before pushing, but I'm planning to come back when behavior would be more transparent or when I'll make sure that every project I work on is correctly formatted all the time :)