public static readonly Lazy<Func<Type, FieldInfo, Type>> TypeISerializeTranslateLazy = new Lazy<Func<Type, FieldInfo, Type>>(
            () => (type, fieldInfo) =>
                  {
                      var tt = type.GetInterfaces().Where(a => a.IsGenericType && a.GetGenericTypeDefinition() == typeof(ISerializeTranslate<>));
                      var enumerable = tt as Type[] ?? tt.ToArray();
                      return enumerable.SingleOrDefault(a => a.GetGenericArguments().First() == fieldInfo.FieldType);
                  });

using System;
using System.Diagnostics;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            // не синглтон
            var objFirst1 = new MustBeSingletonFirst();
            var objFirst2 = new Lazy<MustBeSingletonFirst>().Value;
            var objFirst3 = new Lazy<MustBeSingletonFirst>(() => new MustBeSingletonFirst()).Value;
            Debug.WriteLineIf(!ReferenceEquals(objFirst1, objFirst2), "не синглтон...");
            Debug.WriteLineIf(!ReferenceEquals(objFirst1, objFirst3), "не синглтон...");
            Debug.WriteLineIf(!ReferenceEquals(objFirst2, objFirst3), "не синглтон...");

            // синглтон
            // compile time: cannot access private constructor
            //var objSecond1 = new MustBeSingletonSecond();
            // runtime: MissingErrorException, тк Activator.CreateInstance
            //var objSecond2 = new Lazy<MustBeSingletonSecond>().Value;
            // compile time: : cannot access private constructor
            //var objSecond3 = new Lazy<MustBeSingletonSecond>(() => new MustBeSingletonSecond()).Value;
            var objSecond4 = MustBeSingletonSecond.Instance;
            var objSecond5 = MustBeSingletonSecond.Instance;
            Debug.WriteLineIf(ReferenceEquals(objSecond4, objSecond5), "синглтон...");
        }
    }

    class MustBeSingletonFirst
    {
    }

    class MustBeSingletonSecond
    {
        private MustBeSingletonSecond()
        {            
        }

        private static readonly Lazy<MustBeSingletonSecond> LazyInstance = new Lazy<MustBeSingletonSecond>(() => new MustBeSingletonSecond()); 

        public static MustBeSingletonSecond Instance
        {
            get
            {
                return LazyInstance.Value;
            }
        }
    }
}