Add fenced language syntaxes

[rummik]

This adds fenced syntax highlighting to Nix files by making use of a leading comment on multiline strings.

Edit: This borrows much of the loading code for fenced languages from https://github.com/plasticboy/vim-markdown/

{
  installPhase = /* sh */ ''
    mkdir -p $out
    cp -r ftdetect ftplugin indent syntax $out
  '';

  vimrc = writeText "vimrc" /* vim */ ''
    filetype off
    set rtp+=${vader}
    set rtp+=${src}
   '';
}

[rummik]

Additionally, this resolves #27

[rummik]

I'm not really sure how to reproduce the error showing up on Travis, considering everything runs fine within a nix shell locally

[rummik]

Apparently it runs fine within a nix shell on Travis as well

[LnL7]

This is neat but I don't really want to add support for this unless the syntax is somewhat standardised by the community.

[rummik]

Understandable. I don't know of any community syntax for this though, which is why I went with a leading comment, making it benign for anyone who doesn't use a syntax highlighter with support for it

[Shados]

The leading block comment is I think the only sane approach, but could be slightly awkward in the case that someone already is using a block comment prior to a multiline string; maybe make it so that it scans the comment content for something like ft=sh so it is a little more explicit/flexible?

[rummik]

Some type of prefix could be handy to make it a bit more explicit. As far as flexibility goes though it's able to load any syntax available to vim itself, so long as you either know the name or have an alias that points to it

[SuperSandro2000]

This is the only sane approach which does not modify the string which would cause rebuilds. It can also be combined with vims included markdown fencing to reuse the same syntax highlighting mapping

let g:vim_nix_fenced_languages = g:markdown_fenced_languages

[dasJ]

I've been using this for a couple of months now and one thing I noticed is syntax highlighting breaking after antristrings with the same quoting as the outer strings and sometimes when the editor is split.

[doronbehar]

Is it possible to disable this feature for very large buffers? I noticed this patch causes tremendous slowdown on Nixpkgs' all-packages.nix..

[doronbehar]

This helps me:

commit 490826cd7b80fa4df5ce61a43a2167b9fc7b131a
Author: Doron Behar <doron.behar@gmail.com>
Date:   Sat Apr 22 12:57:07 2023 +0300

    Allow to disable fenced highlighting

diff --git a/ftplugin/nix.vim b/ftplugin/nix.vim
index 134a0e7..2f7fb72 100644
--- a/ftplugin/nix.vim
+++ b/ftplugin/nix.vim
@@ -19,6 +19,10 @@ if get(g:, 'nix_recommended_style', 1)
     \ softtabstop=2
     \ expandtab 
 endif
+ 
+if get(b:, 'nix_disable_fenced_highlight', 0)
+    finish
+endif
 
 " Borrowed from vim-markdown: https://github.com/plasticboy/vim-markdown/
 if exists('g:vim_nix_fenced_languages')

[pinpox]

I'm still very interested in this feature, any chance to get it merged?

[equill]

Looking into this now.

[agentx3]

Does lua syntax fencing work for anyone else? For some reason mine really hates right parentheses

[Ma27]

Thanks a lot for the beautiful work!

I had some thoughts about this and I'm somewhat interested in getting things ready:

• as @LnL7 already stated, I'm also rather hesitant about merging this as-is considering that this plugin is the de-facto standard for syntax highlighting on nix[1] and I don't feel well with introducing a new standard noone else has agreed on. We should at least discuss this with the maintainers of nix-mode[2] and the vscode integration[3] to cover the vast majority of editors. Perhaps we should even discuss this on nixpkgs itself. That'd also have the nice side-effect that it would be OK to introduce these tags where appropriate (and we could benefit from proper syntax highlighting at way more places).
  So ccing @matthewbauer @jnoortheen what do you think of this approach? It has the benefit that it would work for any kind of expression (and additionally it's clear which language is in use ;-) ). We should probably open up a discussion in nixpkgs itself for this, but I'd like to hear your opinion first.
• I can confirm the lua issue @agentx3 has reported, would you mind looking into it @rummik ?
• I tried this plugin out on all-packages.nix and I didn't get any highlighting at all. Perhaps we should automatically disable this feature for either well-known large files (e.g. yarn.nix, hackage-packages.nix, all-packages.nix) or dynamically switch it off for files >n lines. A static opt-out switch should also exist IMHO.
• Question: has anybody investigated whether an LSP can be thrown against e.g. a block of Python code? Didn't work out of the box for me (using latest nvim-lspconfig and neovim 0.9.1), but I haven't looked closely, yet.

In the meantime I'll try to take a look at the code itself :)

[1] NixOS/nixpkgs@0b5a0cb, vim/vim@86b4816#diff-5202ae314163489b5d9872596ccd1bcd9ec8215c64722447dc7ba3b6cbceadd5
[2] https://github.com/nixos/nix-mode
[3] https://github.com/nix-community/vscode-nix-ide

[LnL7]

A static opt-out switch should also exist IMHO.

Perhaps it's even best to make this opt-in instead. Performing syntax highlighting on string contents makes interpolation much harder to see which I feel like is something more common than its syntax complexity. For large code blocks it seems better to use a dedicated file, which also allows regular linting, lsp, etc. tools to be used.

[Ma27]

This is actually a very good point. Constructs such as ''${ will actually cause highlighting problems as well.

[jakehamilton]

I would love to see this merged in as an opt-in feature. Currently it can be quite difficult to work with language snippets that aren't directly in a mkDerivation phase. Adding such a feature, but not enabling it by default seems like a decent solution to me.

[doronbehar]

I rarely use /* sh */ in my code, due to the problem mentioned above regarding constructs such as ''${, but I enabled this feature in my fork's master branch, with a small addition:

if get(b:, 'nix_disable_fenced_highlight', 0)
    finish
endif

Right before most of the code added here begins. This enables me to disable this feature for large files for example.

[donovanglover]

FWIW I was able to fix the Lua parentheses problem with rainbow-delimiters.nvim, available in nixpkgs.