Highlighting text with the <mark> element

[srid]

Would this be an acceptable extension to contribute in order to support highlighting of inline elements using the HTML <mark>?

Hello world; ==this part of the sentence== is highlighted in yellow due to use of the `<mark` tag

It seems to require a change to Pandoc, by adding a new Inline constructor, similar to Superscript, which I would be happy to contribute too.

cf. https://talk.commonmark.org/t/highlighting-text-with-the-mark-element/840

[jgm]

Anything that involves a change to the pandoc AST is very involved. Changes would be required not just to pandoc-types, but to the majority of modules in pandoc. We are generally very conservative about such changes.

One option that works with current pandoc is to use a bracketed span with attributes, [this text is highlighted]{.highlight}, and converting it to RawInline (Format "html") "<mark>", innercontents, RawInline (Format "html") "</mark>" using a filter, if the target format is HTML5 (check global FORMAT in a lua filter).

[jgm]

I'd consider a syntax extension for == in commonmark-extensions -- since this is started to get wider support -- but the pandoc change would be more controversial.