UnificationPolarity.cs

using System;

namespace UnificationPolarity
{
    public static class Class1
    {
        public static IConvertible foo(IConvertible arg) =>
            arg;

        public static Func<IConvertible, IConvertible> bar(Func<IConvertible, IConvertible> arg) =>
            arg;

        public static Func<Func<IConvertible, IConvertible>, Func<IConvertible, IConvertible>> baz(Func<Func<IConvertible, IConvertible>, Func<IConvertible, IConvertible>> arg) =>
            arg;

        public static void test()
        {
            Func<string, object> aaa = foo;
            Func<Func<object, string>, Func<string, object>> bbb = bar;
            Func<Func<Func<string, object>, Func<object, string>>, Func<Func<object, string>, Func<string, object>>> ccc = baz;
        }
    }
}