Getting value from Literal/Const

[TheAngryByrd]

Let's say I have the following code in my Types.fs file.

module A = 
    let [<Literal>] MyConst = "Hello"
    type MyAttribute(thing : string) =
        inherit System.Attribute()
        let _thing = thing
    type Thing = {
        [<MyAttribute(MyConst)>]
        Foo : string
    }

When looking at the AST of this code, the attributes for the field Foo:

{ Attributes =
   [{ TypeName =
                LongIdentWithDots
                  ([MyAttribute],
                   [])
      ArgExpr =
               Paren
                 (Ident MyConst,
                  tmp.fsx (8,25--8,26) IsSynthetic=false,
                  Some
                    tmp.fsx (8,33--8,34) IsSynthetic=false,
                  tmp.fsx (8,25--8,34) IsSynthetic=false)
      Target = None
      AppliesToGetterAndSetter =
                                false
      Range =
             tmp.fsx (8,14--8,25) IsSynthetic=false }]
   Range =
          tmp.fsx (8,12--8,36) IsSynthetic=false }

I get told that the data in the Attribute is MyConst. Do you know if there is a way I'd be able to get the value from that?

[Zaid-Ajaj]

This is how I do it in the Npgsql analyzer

[TheAngryByrd]

Thanks I'll give that a shot!

[TheAngryByrd]

Oh looks like I don't have access to the symbols only the ParsedInput.

Maybe Myriad should adopt the same structure from the Analyzers.SDK?

[7sharp9]

I would rather not have to type check the file and extract symbols thats the super slow part of the compiler, probably better to create some form of backtrack or binding dictionary.

[Krzysztof-Cieslak]

I don't even think the problem is that it's the slow part of the compiler, which wouldn't be an as big issue given Myriad is run as part of build process - but huge issue is that we would need to parse project files to perform type checking. Which as you all know is not the best part of the F# community tooling ecosystem ;]

[7sharp9]

I don't think I'll get to this, up for grabs if anyone ever wants to do it, not me though.