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Cannot use Literal attribute in F # signature file (.fsi)

I cannot define a literal in the F # signature file.

I have a file File.fsas shown below:

module Thingo =
  [<Literal>]
  let hello = "world"

I need to create a signature file for it, so I initially tried this ( File.fsi):

module Thingo =
  [<Literal>]
  val hello : string

This caused the following error in File.fsi:A declaration may only be the [<Literal>] attribute if a constant value is also given, e.g. 'val x : int = 1'

I gave this:

module Thingo =
  [<Literal>]
  val hello : string = "world"

The line after the announcement val helloreceived an error:Incomplete structured construct at or before this point in signature file. Expected incomplete structured construct at or before this point or other token.

Therefore, I do not like to assign values ​​in the signature file (or I do not know how to assign a value, this is very possible).

The docs say that I need to somehow assign a value to the signature:

If an attribute is used Literal, it must appear both in the signature and in the implementation, and the same literal value must be used for both.

( https://docs.microsoft.com/en-us/dotnet/fsharp/language-reference/signatures)

( --sig build) :

module EventSchema = begin
    [<LiteralAttribute ()>]
        val id : string
end

, .

! .

+6
1

, "=". , . F # inferrence.

module Thingo
  [<Literal>]
  val hello= "world"


namespace My.App.Modules

module Thingo =
  [<Literal>]
  val hello = "world"
-1

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