Get types available at current scope

[OkayX6]

Hi,

I don't know if it's difficult to do, but it'd be great to have something similar to GetDeclarationsAlternate https://github.com/fsharp/FSharp.Compiler.Service/blob/master/src/fsharp/vs/service.fsi#L173 (that is used in intellisense), but that returns a list of FSharpSymbol instead.

It would make it easier to implement these code generation helpers:

• http://vfpt.uservoice.com/forums/247560-general/suggestions/5802615-generate-stubs-for-record-types
• http://vfpt.uservoice.com/forums/247560-general/suggestions/5802613-generate-all-match-cases-for-union-types

We would filter them by let say, union types, record types...

Otherwise, we have to rely on syntax tricks so that the type inference can guess the type, and sometimes its clumsy (like there where I have to give hints to the type inference: fsprojects-archive/zzarchive-VisualFSharpPowerTools#365)

Thanks!

[dungpa]

Yes, please expose this functionality. Relying on syntax tricks is ugly and error-prone.

[vasily-kirichenko]

+1 for this. We could implements many useful features in VFPT based on this.

[dsyme]

So there are a few ways to interpret this request.

1. You want FCS to return all the unqualified symbols at a location (e.g. all values such as v, namespaces like System etc.), akin to GetDeclarationsAlternate. This would presumably depend on the opened modules/namespaces, and accept the same input parameters as GetDeclarationsAlternate (for example, so the declarations can be optionally qualified by a path like Microsoft.FSharp).
2. You want to find all the record/union types in any referenced assembly (or in the current assembly) regardless of whether modules/namespaces have been opened.
3. Given some type text like "new IFoo", you want to find the symbol for "IFoo". THis is essentially Support getting type arguments of generic interfaces #136.
4. Given some text like "match expr with " you want to find the inferred type of "expr" without resorting to too many syntax hacks.

I'm pretty sure you want option (1), option (3) and option (4), though it would be good to clarify. But I thought I'd also mention that for option (2), it may be possible to make a lot of progress by looking at any of the following and scraping the returned information for record/union/... definitions. It feels like many interesting helprs could be based on this sort of information.

• Get all the referenced assemblies:

  wholeProjectResults.ProjectContext.GetReferencedAssemblies()
  

• Get the whole inferred signature of a project:

  wholeProjectResults.AssemblySignature
  

• Get the inferred signature of a project up to and including the file just checked:

  checkResults1.PartialAssemblySignature
  

(Note, if you do traverse all the information in a signature, then beware that when using type providers the logical size of a signature may be very large or even infinite, and traversing the object model may force the evaluation of more of the signature. Care must be taken. It may be that we have to add information into symbols to say "only get this information if it is available yet", or that you should use IsProvided to limit your traversal)

Separately, the active list of "open" declarations (including AutoOpen declarations) at a particular location is not currently available from FCS (though is not too hard to add), but I suspect most type-related IDE features should work irrespective of whether the module/namespace containing the tyoe has been opened or not (though the text produced may vary depending on whether it has).

Cheers!
Don

[dungpa]

Hi Don,

I very much like option (1). It's like another version of GetDeclarationsAlternate with rich type/symbol information. It provides us a lot of flexibilities to take advantages of. On a related note, most of editor operations such as GetDeclarationsAlternate predates FCS. Now that FCS has much more capabilities, why don't we provide richer interfaces and let clients decide how to consume information.

Option (3) and (4) are useful in certain situation where we probe symbols for more information. If FCS exposes typed ASTs via object models, I'm not sure they are even needed.

[dungpa]

All these options are extremely useful for typed-related IDE features. Any chance that they are added in the next version of FCS?

[7sharp9]

Recently I added GetDeclarationSymbols, I think the symbol API needs to be augmented for this type of operation too.

[dungpa]

There is a lot of redundancies in results from GetDeclarationSymbols.How can we filter them in a sensible way?

[7sharp9]

It uses the same filter as GetDeclarations so they should match, to get more specific I guess a better ident island.

[dsyme]

@7sharp9 implemented this in #281 and others