Support syntax highlighting in examples about ex_doc

[josevalim]

Don't we have one of those javascript highlighting tools that accept either textmate or pygments source files?

[pminten]

It's a decent bit of work. Serendipitously Josh Adams is working on highlight.js support for Elixir.

Basic highlight.js integration should be simple enough.

[josevalim]

Awesome! For me something like highlight.js would be the easiest to bundle into ExDoc.

[vanstee]

Oh yeah highlight.js is a great option.

I'll try to put this together once this pull request gets merged: highlightjs/highlight.js#317 Thanks for working on this @knewter.

[josevalim]

Fantastic job @knewter! ❤️ 💚 💙 💛 💜

[alco]

Any chance we could use pygments (if it is installed on the user's system)?

[josevalim]

That's one option, there is another issue though: how can we guarantee it is elixir syntax since we don't tag languages?

[alco]

We can set default language for all code blocks. Pygments could also guess the language by contents.

[alco]

Also, there has to be an option of cancelling highlighting if an error token is found. I saw this behaviour in sphinx. So we set elixir for all code blocks, but if there is a shell code example (containing $), the dollar will not be recognized by the elixir lexer, and the whole code block will be left unhighlighted.

[alco]

Just for the record: adding support for pygments at the current stage would be rather complicated. To make it work for sundown and pandoc, we'd need to scan the resulting html and replace code blocks in it.

Using markdown converter written in Elixir with support for user-supplied filters would be best.

So currently, the most pragmatic approach is to bring highlight.js up to date with modern Elixir and use that. /cc @knewter

[dignifiedquire]

As far as I understand one could use pandoc (if installed) to take care of any syntax highlighting by setting the flag

--indented-code-classes=CLASSES
Specify classes to use for indented code blocks–for example, perl,numberLines or haskell. Multiple classes may be separated by spaces or commas.

to elixir and adding elixir support to pandoc / highlighting-kate. For that reason I've started working on doing exactly that:
dignifiedquire/highlighting-kate@1955130

It's not ready for prime time yet, but I hope to have something reasonable in the next few days.

[whatyouhide]

If I understand correctly, this should be now solved since ex_doc is using highlight.js (with Elixir support) to highlight code examples in the documentation. Should we close this?

[vanstee]

Yep good call. Here's the relevant PR: #168

Thanks for following up @whatyouhide.

[whatyouhide]

@vanstee no problem, my pleasure!