(*
 * A generic function that tests equality for any two tuples or lists, such
 * that the objects are the same except for one element.
 *
 * BUT HEY, THIS CANT WORK WITHOUT ML-LIKE GENERIC TYPES, AT LEAST FOR RECORDS
 * IT CANT. 
 *
 * UPDATE: It's not exactly clear what we were originally trying to prove here.
 * What we have proved is not a big suprise -- that at present, this file
 * checks fine since type AnyList is fully generic, and '=' is fully overloaded
 * for (non-function types at least).  However the notion that we could have a
 * function that tests for equality of any two-tuples will only work because
 * built-in equality is overloade for all tuple types.  HOWEVER, we have not
 * crossed the line in allowing runtime interrogation of tuple types in order
 * to provide generic access to their fields.
 *)
function XEqYExceptFor(x:AnyList, y:AnyList, elem:integer) =
    forall (i in [1..#x])
	if (i = elem)
	then x[i] != y[i]
	else x[i] = y[i];

(*
 * BUT HEY again, let's try a bit harder to make it work.
 *)
obj Any;
obj AnyList =  Any*;
(* obj AnyTuple is tuple of Any; *)