Discriminated Union Fun

// This is proof-of-concept code for using the F# from C#, so I'm putting
// the relevant snippets together in this one file

// F# code
namespace IntroDUs

module IntroDUs = 
    // This is a method of packing primitives into discriminated unions
    // and using an extension property on the DU to provide direct access
    // to the packed data. 

    // You can use the packed data in the DU for strongly typed pattern matching
    // and other useful DU features. 

    type FirstName = FirstName of string with
        member this.Value = 
            this |> (fun (FirstName x) -> x)

    type LastName = LastName of string with
        member this.Value = 
            this |> (fun (LastName x) -> x)

    type Person = {
        First: FirstName
        Last: LastName
    }

    module ExampleUse = 
        // This creates a list of strongly typed Person records 
        // with single case DU properties
        let somePeople = 
            [
                { 
                    First = FirstName "Bob"
                    Last  = LastName "Jones"
                }

                {
                    First = FirstName "Sarah"
                    Last  = LastName "Smith"
                }
            ]     
        



// C# code

using System.Linq;

namespace ExampleUse 
{
    public class Example
    {
        public void ReadFromFsharp()
        {
            var bob = IntroDUs.IntroDUs.ExampleUse.somePeople.ToList()[0];
            // The "value" extension property allows us to directly
            // access the DU values easily from C#
            string bobsFirstName = bob.First.Value;
            string bobsLastName = bob.Last.Value;
        }
    }
}