Lenses

FunctionalObject1.cs

public partial class FunctionalObject<T> where T: class, ICloneable, new()
    {
        private readonly T _object;
        private readonly Queue<Action<T>> _modifiers;
        public FunctionalObject(T @object)
        {
            _object = @object;
            _modifiers = new Queue<Action<T>>();
        }

        public FunctionalObject<T> With(Action<T> selector)
        {
            this._modifiers.Enqueue(selector);
            return this;
        }
        public T GetValue()
        {
            var result = _object.Clone() as T;
            if (!ApplyModifiers(this)) 
                return null;

            return result;

        }
}

FunctionaObject2.cs

public partial FunctionaObject2 where T: class, ICloneable, new()
{
   public static Func<FunctionalObject<T>, P> NewGetLens<P>(Func<T, P> func)
        {
            return (o => func.Invoke(o.GetValue()));
        }
        
  public static Func<FunctionalObject<T>, FunctionalObject<T>> NewSetLens(Action<T> func)
        {
            return o => o.With(func);
        }
}

LensModel.cs

class Model:ICloneable
    {
        public string Item { get; set; }
        public int Price { get; set; }

        public object Clone()
        {
            return new Model()
            {
                Price = this.Price,
                Item = this.Item
            };
        }
    }