Grammar checking in Emacs

[Daniel Martín]

Emacs has good support for spell checking text written in multiple
languages.  However, there is currently no support for grammar checking,
and I think that feature may be useful for people writing long documents
and books with Emacs.

I've found a few discussions in emacs-devel about grammar checking, and
the general feeling in the past has been that grammar checking is not
useful enough, because the tools only provide some text linting
functionality that just offers some basic style suggestions.

The question is if those feelings about grammar checking still hold
true.  I think one of the most popular free programs to do grammar
checking is LanguageTool (https://languagetool.org).  I've quickly
tested it and it detected some non-trivial grammar mistakes, in English
and Spanish at least.  I didn't see false positives, which is a good
thing in this kind of tools.  You can try the tool from its website
without installing it on your computer.

Is there interest in having this feature in Emacs?  Perhaps as an ELPA
package, if the technology is not mature enough to have it in Core?