Trying to workaround missed higher-kinded type parameters in c#

Functor.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace FunctorTest
{
    public interface SingleParamPolymorph<T> { }
    public interface TwoParamsPolymorph<T, U> { }

    /// <summary>
    /// REalization of \Haskell's Functor:
    /// class Functor f where
    ///     fmap :: (a -> b) -> f a -> f b
    ///     C# version DOESNT COMPILE
    /// interface IFunctor<T> {
    ///     T<B> FMap<A, B>(Func<A, B> f, T<A> a);
    /// }
    /// class ListFunctor<T> : IFunctor<List<>> {
    ///     List<B> FMap<A, B>(Func<A, B> f, List<A> a) {
    ///         ...
    ///     }
    ///}    
    /// </summary>
    /// <typeparam name="ACONT"></typeparam>
    /// <typeparam name="BCONT"></typeparam>
    /// <typeparam name="A"></typeparam>
    /// <typeparam name="B"></typeparam>
    public interface IFunctor<ACONT, BCONT, A, B>
        where ACONT : SingleParamPolymorph<A>
        where BCONT : SingleParamPolymorph<B>
    {
        BCONT FMap(Func<A, B> f, ACONT a);
    }



    public class Container<T> : SingleParamPolymorph<T>
    {
        public Container(T val)
        {
            Value = val;
        }
        public T Value { get; set; }
    }

    public class MyList<T> : List<T>, SingleParamPolymorph<T>
    {
        public MyList()
        {

        }

        public MyList(List<T> from)
        {
            this.AddRange(from);
        }
    }

    public class ContainerFunctor<T> : IFunctor<Container<T>, Container<T>, T, T>
    {
        public Container<T> FMap(Func<T, T> f, Container<T> a)
        {
            return new Container<T>(f(a.Value));
        }
    }

    public class ListFunctor<A, B> : IFunctor<MyList<A>, MyList<B>, A, B>
    {
        public MyList<B> FMap(Func<A, B> f, MyList<A> a)
        {
            return new MyList<B>(a.Select(x => f(x)).ToList());
        }
    }

    class Program
    {
        static void Main(string[] args)
        {
            var lst = new MyList<String>();
            lst.Add("aa");
            lst.Add("bbb");
            Func<String, int> f = x => x.Length;

            var res = new ListFunctor<String, int>().FMap(f, lst);
            Console.WriteLine(res[0]);
            Console.WriteLine(res[1]);
            Console.ReadLine();
        }
    }
}