Improve Gleam syntax highlighting

[JosephTLyons]

This issue was moved from the zed repository, originally filed by @ghivert:

Hi! I'm not sure where to talk about the subject, so I prefer open an issue. 🙂

Those days, I was trying to see if we can improve the syntax highlighting for Gleam. Currently, in the syntax highlighting, we got all functions calls highlighted as records access when they're done in a fully qualified way.

import my_package
pub fn main() {
  my_package.function() // <-- On Zed, this is highlighted as record property, and not function.
}

What do you think to modify the Gleam syntax highlighting (i.e. highlights.scm) to highlight every functions used from records with proper functions highlighting? I tried to implement it here to figure out how it can be. (I'm absolutely not sure it's correctly implemented, I mainly wanted to prove myself it was possible.) I also joined two screenshots on how it feels directly in the editor.

I know tree sitter can not know if the field is a function or not (because we can have a constant, so calling it will result in an error), but the LSP could take care of this, and — in my opinion — having a proper function highlighting for fields called as functions will improve readability.

Function syntax highlighted

Record syntax highlighted

[JosephTLyons]

@ghivert

[ghivert]

Link is broken, correct link.

To expand a bit, I think the syntax highlighting should help the reader to easily distinguish the context. When you encounter something like function_call() or namespace.function_call(), having them highlighted as function call would help, because that's the information you want to transmit to your reader. Thanks to tree sitter, we can even highlight pieces of code like data |> namespace.function_call correctly. We can sometimes have false positive: when writing data |> struct.field, field will be highlighted as a function call even if it's not a function, but the LSP will trigger a warning. I think it's safe to consider that most of the time, we're spending time to read code, and because of the nature of Gleam, the code will be correct (thanks to the compiler). As such, it would make sense to favour easing of reading.

I'm curious to hear your opinions here. Of course, I'd be happy to open a proper pull request if we agree on this. 🙂

[JosephTLyons]

I updated the link and made it known the text came from you.