Fix in syntax.md. CSS adjustments

[pikinier20]

closes #14697

@MarcinAman

[KacperFKorban]

I think that we have to update the highlight.pack.js since it doesn't include support for ebnf ATM. Though for some reason it includes OCaml and Ruby for example 🤔

Overall, I think that the change to styling is a big improvement 😄

[pikinier20]

I think that we have to update the highlight.pack.js since it doesn't include support for ebnf ATM. Though for some reason it includes OCaml and Ruby for example 🤔

Overall, I think that the change to styling is a big improvement 😄

highlight.js doesnt provide support to ebnf, there's only bnf supported

[KacperFKorban]

Hmmm, there is some code that looks likebnf support in hljs repo.
rel: highlightjs/highlight.js#1255

[pikinier20]

Tried to bump hljs version and use ebnf syntax highlighting for this snippet but it broke:

[pikinier20]

Ok, just manually changed the hljs rules and added semicolons at the end of rules and got sth better:

Probably there's a way to remove the semicolons but it would require some work on hljs rules

[pikinier20]

this looks nice

[odersky]

I am afraid the change of semicolons completely butchered the grammar. The grammar is the core piece of specification. Every symbol counts. Please don't do wholesale changes like this without consulting more broadly.

[odersky]

I find it very problematic that a PR pretending to be style fix can change a core piece of the specification and all docs without passing proper review. We have to review how we deal with PRs and how we can avoid such blunders in the future.

[odersky]

I'll revert the commit for now, and re-open the issue.

[odersky]

I see now that all the ; are meta-symbols for the EBNF, not symbols of the grammar itself. But we never did it that way. Every Java and Scala grammar I know is written without ; terminators, for good reason: The ; is too easily confused with a symbol in the grammar. So, please don't do sweeping changes to the docs like this.

[odersky]

I think in general if it is a change that affects docs wholesale it has to be discussed in team with the authors of the docs. I find it very frustrating to see docs I spent many hours writing massacred like this.

[pikinier20]

I see now that all the ; are meta-symbols for the EBNF, not symbols of the grammar itself. But we never did it that way. Every Java and Scala grammar I know is written without ; terminators, for good reason: The ; is too easily confused with a symbol in the grammar. So, please don't do sweeping changes to the docs like this.

The highlight.js tool which we use to highlight the syntax, is not very sophisticated and uses basic regexes to consume grammars. The authors of EBNF highlighting added these semicolons in order to simplify rules and not use lookaheads etc. (You need to know when the rule ends to parse next token as a LHS of next rule)

I'm sorry about this situation. I guess we can just replace the semicolons with some invisible unicode character or any other symbol that won't be misleading.