What is the simplest way to access data of an F# discriminated union type in C#?

Question

I\'m trying to understand how well C# and F# can play together. I\'ve taken some code from the F# for Fun & Profit blog which performs basic validation returning a discr

Answer 1

I'm using the next methods to interop unions from F# library to C# host. This may add some execution time due to reflection usage and need to be checked, probably by unit tests, for handling right generic types for each union case.

1. On F# side

type Command = 
     | First of FirstCommand
     | Second of SecondCommand * int

module Extentions =
    let private getFromUnionObj value =
        match value.GetType() with 
        | x when FSharpType.IsUnion x -> 
            let (_, objects) = FSharpValue.GetUnionFields(value, x)
            objects                        
        | _ -> failwithf "Can't parse union"

    let getFromUnion<'r> value =    
        let x = value |> getFromUnionObj
        (x.[0] :?> 'r)

    let getFromUnion2<'r1,'r2> value =    
        let x = value |> getFromUnionObj
        (x.[0] :?> 'r1, x.[1] :? 'r2)

2. On C# side

        public static void Handle(Command command)
        {
            switch (command)
            {
                case var c when c.IsFirstCommand:
                    var data = Extentions.getFromUnion(change);
                    // Handler for case
                    break;
                case var c when c.IsSecondCommand:
                    var data2 = Extentions.getFromUnion2(change);
                    // Handler for case
                    break;
            }
        }