Technically its passing 'a list -> 'a list, and only becoming an int array because thats the final input value. The fsharp functions are closer to the C# functions Func<List<IComparable>, List<IComparable>>
Or to be even mooooooore pedantic the fsharp functions would probably be written to be seq<'a> -> seq<'a>, so that would be Func<IEnumerable<T>, IEnumerable<T>> where T : IComparable<T> :)
