.cs

using System;
using System.Collections.Generic;
using System.Linq;
using LanguageExt;

namespace PracticalCSharp.Either.Monad.Exception
{
    public static partial class FunctionalExtensions
    {
        public static T GetOrThrowException<T>(this Either<string, T> @either)
           => @either.Match(
             Right: (T value) => value,
             Left: (string error) => throw new System.Exception(error)
        );
    }

    public class Client
    {
        public int Id { get; set; }
        public string Name { get; set; }
        public int EmployeeId { get; set; }
    }
    public class MockClientRepository
    {
        List<Client> clients = new List<Client>{
                    new  Client{Id=1, Name="Jim",  EmployeeId=1},
                    new  Client{Id=2, Name="John", EmployeeId=4}
                };

        public Either<string, Client> GetById(int id)
        {
            Option<Client> t = clients.SingleOrDefault(x => x.Id == id);
            return t.ToEither("no Client Found");
        }
    }

    public class Controller
    {
        MockClientRepository clients = new MockClientRepository();
        public string GetAssignedEmployeeNameById(int clientId) =>
          clients
                .GetById(clientId)
                .Map(client => client.Name)
                    .GetOrThrowException();
    }
    public class Demo
    {

        public void Run()
        {
            try
            {
                var assignedEmployeeName = new Controller().GetAssignedEmployeeNameById(1);
                    assignedEmployeeName = new Controller().GetAssignedEmployeeNameById(3); //throws exception
            }
            catch (System.Exception e)
            {

                //throw;
            }


        }
    }
}