rewrite Ceylon's build-in type Tuple

MyTuple.ceylon

class MyTuple<out Element, out First, out Rest = []>
		(first, rest)
		extends Object()
		satisfies List<Element>
		given First satisfies Element
		given Rest satisfies List<Element>
{
	"The first element of this tuple. (The head of the 
	    linked list.)"
	shared actual 
	First first;
	
	"A tuple with the elements of this tuple, except for the
	 first element. (The tail of the linked list.)"
	shared actual
	Rest rest;
	
	shared actual native 
	Integer lastIndex => rest.size;
	
	shared actual native 
	Integer size => 1 + rest.size;
	
	shared actual
	Element? getFromFirst(Integer index)
			=> switch (index <=> 0)
			case (smaller) null
			case (equal) first
			case (larger) rest.getFromFirst(index - 1);
	
}

MyTuple<Integer, Integer, Empty> myTuple = MyTuple(1, empty);

MyTuple<String|Integer, String, MyTuple<Integer,Integer,Empty>> myTuple2 =
		MyTuple("text", MyTuple(1, empty));