FSFormatting.Literate with code that is not F#

[kblohm]

Hi,
while the Markdown HTML Formatter formats codeblocks as <pre><code class="language-***">...</code></pre>,
the Literate module uses <pre class=\"fssnip\"><code lang=\"%s\">%s</code></pre> (lang attribute instead of class.) This makes it very inconvenient to use alternative formatting tools like prism.js or highlight.js to format code that is not F#. Is this behaviour intended?

[matthid]

Probably just an oversight. There are multiple places like this...
One note however: For F# code we basically have our own html code generation (to insert tool-tips for example), which is already inconsistent.

[kblohm]

The tooltips are a nice gimmick, but the code generation makes it much harder to add something like a "syntax" property to each metadata element and just format that when it is actually needed. The microsoft docs for F# do this and i think it is pretty useful for example.
While it might be nice to have more control over the F# output i think there are enough tools that do a decent job at it and are able to render other languages as well.

[matthid]

On one side I agree. On the other hand one advantage of fsf (in theory) is that we can provide deep-links in code samples to the API-reference documentation (and I think people are doing that) as well as to inspect types of variables in the code. This is way more powerful than "simple" colorization.

[github-actions]

🤖 This is an automated response from Repo Assist.

Good news: this issue appears to be resolved in the current codebase. Looking at src/FSharp.Formatting.Markdown/HtmlFormatting.fs, code blocks with a specified language now render with the standard language-xxx class format:

let langCode = sprintf "language-%s" (htmlEncodeQuotes language)
ctx.Writer.Write(sprintf "<pre><code class=\"%s\">" langCode)

This is the format expected by both [highlight.js]((highlightjs.org/redacted) and [prism.js]((prismjs.com/redacted) for syntax highlighting. So ```python in a Markdown file will render as <pre><code class="language-python">.

The F# code blocks continue to use the custom tooltip/hyperlink rendering pipeline (as noted in the earlier comments), which has richer semantics than general-purpose syntax highlighters can provide.

If you're on a recent version of FSharp.Formatting and still seeing the old lang attribute, please let us know with your version number. Otherwise, this issue could probably be closed.

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