sub add_pet {
  state $check = compile_named(
    name    => Str,
    species => Str,
    age     => Optional[Int],
  );
  my $args = $check->(@_);

  ...; # do stuff with $args hashref
}

##</code><code>##

my $type = CycleTuple[Str, ArrayRef, Int];
$type->assert_valid( [ "foo", [], 42, "bar", [], 21 ] );  # ok
$type->assert_valid( [ "foo", [], 42, "bar", [], 2.1 ] ); # throws exception