What is the Enum.GetName equivalent for F# union member?

Question

I want to get the equivalent of Enum.GetName for an F# discriminated union member. Calling ToString() gives me TypeName+MemberName, which isn't exactly what I want. I could substring it, of course, but is it safe? Or perhaps there's a better way?

Answer 1

You need to use the classes in the Microsoft.FSharp.Reflection namespace so:

open Microsoft.FSharp.Reflection  ///Returns the case name of the object with union type 'ty. let GetUnionCaseName (x:'a) =      match FSharpValue.GetUnionFields(x, typeof<'a>) with     | case, _ -> case.Name    ///Returns the case names of union type 'ty. let GetUnionCaseNames <'ty> () =      FSharpType.GetUnionCases(typeof<'ty>) |> Array.map (fun info -> info.Name)  // Example type Beverage =     | Coffee     | Tea  let t = Tea > val t : Beverage = Tea  GetUnionCaseName(t) > val it : string = "Tea"  GetUnionCaseNames<Beverage>() > val it : string array = [|"Coffee"; "Tea"|] 

Answer 2

@DanielAsher's answer works, but to make it more elegant (and fast? because of the lack of reflection for one of the methods), I would do it this way:

type Beverage =     | Coffee     | Tea     static member ToStrings() =         Microsoft.FSharp.Reflection.FSharpType.GetUnionCases(typeof<Beverage>)             |> Array.map (fun info -> info.Name)     override self.ToString() =         sprintf "%A" self 

(Inspired by this and this.)