How does the union, class and record intellisense tool tip signature work?

[faldor20]

What

I know this is a strange request, but I have been trying to port a few key features from fsac to FSharpLanguageServer and would love some help.
Notably the function and type signature display in the IntelliSense window:

I got function signatures working fine using the extractSignature function from TipFormatter.fs
However, I can't seem to find the code for record/union/class signatures.

FSAC

FSLSP

If anyone could point me in the right direction that would be amazing

Why

I seem to have a lot of trouble with fsac, I have 3 dev machines that I use and on all of them regardless of the project, I have a lot of trouble. Mostly it is extremely slow, or just throws exceptions constantly. Especially on larger projects
I have looked at some of the discussions around this #361 and it seems there is little interest in resolving perf problems.
So after looking at the codebases, it seemed FSLSP was far simpler and easier to understand and so I thought I may as well just try to port the few features that I am missing over.

I am aware it is a little strange for me to ask for help trying to extend a "competitor" but I am guessing your goal is to supply great f# tooling and for people like me FSLSP is the only way some of the time.

[faldor20]

I actually fixed this by removing some of the code in extractSignature

///Takes a function signature and returns a string with the definition and type signature
let extractSignature (FSharpToolTipText tips) =
    ///This seems to just restrict the tooltip to the first line
    let getSignature (str: string) =
        let nlpos = str.IndexOfAny([|'\r';'\n'|])
        let firstLine =
            if nlpos > 0 then str.[0..nlpos-1]
            else str

        if firstLine.StartsWith("type ", StringComparison.Ordinal) then
            let index = firstLine.LastIndexOf("=", StringComparison.Ordinal)
            if index > 0 then firstLine.[0..index-1]
            else firstLine
        else firstLine
    let firstResult x =
        match x with
        | FSharpToolTipElement.Group gs -> List.tryPick (fun (t : FSharpToolTipElementData<string>) -> if not (String.IsNullOrWhiteSpace t.MainDescription) then Some t.MainDescription else None) gs
        | _ -> None

    tips
    |> Seq.tryPick firstResult
    //I removed this because it restricted signautures to the first line,seemingly for no reason, which chops off descriptions of types
    //|> Option.map getSignature
    |> Option.defaultValue ""

I don't understand why the code here seems to cut off the signature for unions and records. Or why that doesn't actually appear to effect FSAC but did when I added it to FSLSP.
Either way by removing getSignature that limits the tooltip to the first line we now have a working function and type signatures.

[baronfel]

if you look at the tooltip text coming from FCS it's made of several parts: signature, assembly, generic parameter information, etc. What we do here is specifically extracting the signature portion for formatting, because elsewhere in FSAC we have mechanisms for formatting the other parts of the FCS-returned tooltip structure.

[baronfel]

I would like to take exception with some of your comments, however:

little interest in resolving perf problems

FSAC strives for compatibility, but we don't actively hate performance. It's hard to pin down certain causes, that's all. We'd certainly welcome any specific cases that people can report, but we're not mind-readers here. We just try to err on the side of compatibility (by way of the proj-info cracking) rather than use the FCS APIs (which are nowhere near as broadly-compatible).

[faldor20]

@baronfel
Thanks, I suspected it was going to be something like that.

I'm not sure I understand what you mean by compatibility? I have never had a project that FSLSP wouldn't open or anything like that. Infact I often use it for very large projects where FSAC can become unusably slow.

I'm sure its not that you don't care at all about performance. I certainly did get the impression from #361 that it was not a priority. I totally agree that features are important too but for what I personally use, intelisense, linting, gotdef, find reference etc. Other than a few problems like the one I am trying to fix here FSLSP does the same thing and is just faster. But maybe I'm missing out on some features I don't know about? 😅

I would love to try and create issues about some of the problems I have but they are often quite nebulous and hard to pinpoint. I get a hell of a lot of exceptions in the logs from FSAC, but I am often not sure if they are "acceptable exceptions" or "unacceptable exceptions"

For me personally I would love to be helpful and try and fix those problems, I just see less problems with FSLSP that need fixing, and I think I would actually be able to fix them. Mostly it is just a process of porting over a few features from FSAC. The only real difference I notice, in my usage,(now that I have these type tips fixed) is the better hover popup formatting and ability to show what types generics are in that situation( super cool feature btw 👍 ).

I'm really sorry if I seem overly critical I really do appreciate all the work people have put in and I think it is a great tool, but I think acknowledging these problems is important.

[Krzysztof-Cieslak]

And what's the point of this issue? You are happy with some other project and want to help it? Good for you, you solved your problem, but it's off-topic for this issue board.

Also I'd recommend to stop making uneducated assumptions about priorities of projects you don't use or contribute to. It may turn out that you miss quite a lot of context... like 10 years of history of the project :-)

[faldor20]

@Krzysztof-Cieslak
I do use this project and have for over 2 years of F# development. I was just try to explain myself.
Obviously the issue is a simple request for a little bit of help, I even acknowledged that it was an unusual request but seemed like something that the people here might be interested in helping with.

If people here are not interested in providing any kind of assistance that's alright. I would have asked on a discord or forum or somewhere more appropriate but I couldn't find one.

I feel I acknowledged I don't really know the history, I can only say what appears to be the case from an outside perspective.

Am I wrong in that assumption? Because if there is a serious effort to improve the perf of ionide I would be happy to help. I just saw FSLSP as more approachable and it appeared to have more low hanging fruit as far as issues go.

[baronfel]

If people here are not interested in providing any kind of assistance that's alright.

Issues aren't really the place for open ended things like this, next time please use the Discussions feature instead for more free-form discussions.

serious effort to improve the perf of ionide

Yes, of course, all the time. It would be folly to reject a contribution that improved performance and didn't regress anything else. That should go without saying. The hard part, as always, is pinpointing the cause, which requires good reproducible reports. This has historically been lacking, shall we say.