fun normalize (x) {
  if x < 0 then -1 else if x > 0 then 1 else 0 fi fi
}

fun f (x) {
  fun (y) {x + y}
}

write (compare (1, 2));
write (compare (2, 1));
write (compare (3, 3));
write (compare (2, "abc")); 
write (compare ("abc", 2)); 
write (compare ("abc", "abc"));
write (normalize (compare ("ab", "abc")));
write (normalize (compare ("abc", "ab")));
write (compare ([], []));
write (compare (A, A));
write (compare (A, B));
write (compare (B, A));
write (compare (A (1), A (1, 1)));
write (compare (A (1, 1), A (1)));

-- not stable: write (compare (f, f));
-- not stable: write (compare (f, f(5)));
-- not stable: write (compare (f(5), f)); 
-- not stable: write (compare (f(5), f(5)));
-- not stable: write (compare (f(5), f(6)));
-- not stable: write (compare (f(6), f(5)));

write (compare ({1, 2, 3}, {1, 2, 3}));
write (compare ({1, [2], [[3]]}, {1, [2], [[3]]}));
write (compare ({1, [2], [[3]]}, {1, [2], [3]}));
write (compare ({1, [2], [3]}, {1, [2], [[3]]}))