LS: hover info for custom types and their constructors

[unknown]

The language server currently doesn't return hover info for custom types and their constructors. It would be useful for the language server to support this.

//// wibble.gleam

type Wibble {
  // ^ wibble.Wibble

  Wibble(Int)
  // ^ fn(Int) -> Wibble

  Wobble(String)
  // ^ fn(String) -> Wibble
}

The proposed behavior above would be consistent with the hover info of type annotations and constructor expressions.

[GearsDatapacks]

Ah, I think that may be a bug. I'm sure I've used that feature before. I'll investigate

[unknown]

Ah, I think that may be a bug. I'm sure I've used that feature before. I'll investigate

I've tested every tagged release dating back to v1.0.0, and none of the versions provided hover info on my machine. Feel free to investigate further, but I'd like to work on this in the meantime!

[GearsDatapacks]

Go ahead! I haven't had a chance to look at it yet

[unknown]

Ran into a small issue with implementing the proposed behavior because RecordConstructor doesn't store any data related to which custom type it's a member of. Not sure if there are other approaches to get the custom type, but alternatively, we can display something similar to rust-analyzer's behavior when hovering enums like the following:

//// wibble.gleam

type Wibble {
  // ^ Wibble

  Wibble(Int)
  // ^ Wibble(Int)

  Wobble(String)
  // ^ Wobble(String)
}

I think this is also more readable and useful.

[unknown]

While working on this, I've also realized that type aliases do not have any hover info. Is this something that we want to support? If so, should I open a separate issue or merge that into this one?