Display the type signature of candidates when doing completion (detail field in CompletionItem)

[jimenezrick]

Hi, (and thanks for creating Eglot!)

I noticed that when using the Haskell language-server it doesn't display the type signatures of the candidates proposed for a completion. Looking at the LSP logs, it seems that the type signatures are added in the detail?: string; field of the completionItem message (see: https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#completionItem).

I suppose each LSP server implementation might be slightly different, but seems that the protocol spec considers that detail field to be used for such purpose.

Is this something Eglot should consider (because I'm not sure)?

I also use company-quickhelp to show documentation popups for each completion candidate, it only displays the candidate documentation without any type signature (ignoring the detail field). Although when displaying the documentation at-point it does then include the type signature, as expected, on top of the documentation text.

Again, just wondering if this is something to consider or maybe a specific quirk of the Haskell LSP server.

Thanks!