Is syntax highlighting for Fortran currently disabled?

Question

This recent question on chemistry.se includes a snippet of Fortran. Contrasting to anticipation, the addition of fortran after the initial three grave accents does not enable the syntax highlighting (do and end do would qualify as keywords here):

h_core = e1ints
do q =1,norb
    do p =1,q
        h_core(p,q) = h_core(q,p) !lower triangular to symmetric
    end do
end do

Following the discussion here, an explicit example how it is supposed to be used, and a check that Fortran per se is considered by highlight.js here, I notice currently none of the following approaches work on chemistry.se.

do i = 1, 5  ! backticks & fortran
   write (*,*) i
end do

do i = 1, 5  ! backticks & f90
   write (*,*) i
end do

do i = 1, 5  ! backticks & f95
   write (*,*) i
end do

On the contrary, python for Python works on the get-go:

for i in range(4):
    print(i)
    if i >= 2:
        print("i .ge. 2")

Question/suggest: may there be (again?) support for syntax highlighting Fortran? Copy-paste of the three Fortran loops e.g., into the standard question box on mattermodelling.se promptly highlights all relevant keywords. Or, is there policy specific to chemistry.se to constrain highlight.js' action to general purpose language Python only?

Answer 1

There is no official support for Fortran highlighting on Stack Exchange, see https://meta.stackexchange.com/a/184109/312770, which mentions that not all languages supported by highlight.js work on SE.

Anyway, from what I can tell, the supposed Fortran highlighting observed on Matter Modeling is not correct. Superficially it looks as if there is syntax highlighting, but notice how the comment is not correctly detected (in fact, it thinks that the word lower in the comment is a keyword).

Most likely, what is happening is that fortran is not recognised as a valid language, which leads to a different language being inferred—which just so happens to also have end and do as keywords. I don't know why the behaviour on Chemistry is different, but in my opinion, no code highlighting wins out over bad code highlighting.

Or, is there policy specific to chemistry.se to constrain highlight.js' action to general purpose language Python only?

No, there isn't, and this isn't under our control anyway. You could try making a feature request on Meta.SE for Fortran highlighting, but unfortunately, the same post linked above suggests that this is unlikely to get any traction.

Answer 2

TL;DR: No, it isn't. Use lang-fortran as identifier.

Also referring to https://meta.stackexchange.com/a/184109/312770 using triple backticks and a language identifier lang-<lang> or tag does switch on code highlighting.

We do not have fortran and hence there is no language highlighting associated with it. At least that is my best guess, as it works(ish?) with lang-fortran:

h_core = e1ints
do q =1,norb
    do p =1,q
        h_core(p,q) = h_core(q,p) !lower triangular to symmetric
    end do
end do

Whether or not this actually works correctly is not something I can judge. I see some colour and that is all that I can say.

If it doesn't work correctly, then that might be an issue on the development platform, iirc gitlab or so and such … . So we need to be sure that this works correctly there first.

I have no idea why this works (out of the gate) for python as there is currently no highlighting associated with it either. I guess this might be a network wide implementation, a best guess condition or default or … . However, this tag shouldn't exist here anyway. So don't get used to it. (And thanks for pointing this out again.)

So while it might be flawed, it isn't blocked, and following the discussion about introducing code highlighting, the consensus was to explicitly specify it, everything works as well as can be expected. (I guess.)

Answer 3

I wrote about how we handle syntax highlighting in an answer on Meta Stack Exchange to a question requesting that we add highlighting for Julia:

Syntax highlighting happens on the client side currently. This means that if we add too many different languages, the size of the distributable gets very large and can make the site slower to load. While any one language might be a good addition, we get enough language requests that if we added them all, we'd have a long list and a big problem.

I've talked with Ben Kelly, one of our Stacks team developers and, while he really hopes to eventually support nearly all languages that highlight.js supports, it'll require some big changes to how we process syntax highlighting and we don't know when we'll be able to get this work scheduled.

I wrote this in August last year and we haven't made any progress and, as far as I'm aware, we haven't scheduled any work to build this in. Assuming that Fortran highlighting is available in Highlight.JS, we should eventually have highlighting for it at some point in the future, but I don't know when that will be.