watch { $b = $#a } { len => 1 }, 'length $#';
is $b, 2, 'array: length $# correctly';
watch { $b = $#a } { len => 1 }, 'length $#';
is $b, 2, 'array: length $# correctly';
$b = watch { pop @a } { set => 1, len => 1 }, 'pop';
is $b, 'y', 'array: pop correctly';
$b = watch { pop @a } { set => 1, len => 1 }, 'pop';
is $b, 'y', 'array: pop correctly';
$b = watch { shift @a } { set => 1, len => 1 }, 'shift';
is $b, 't', 'array: shift correctly';
$b = watch { shift @a } { set => 1, len => 1 }, 'shift';
is $b, 't', 'array: shift correctly';
-watch { my $i; @a = map ++$i, @a; () } { set => 5, len => 1, clear => 1}, 'map';
+watch { my $i; @a = map ++$i, @a } { set => 5, len => 1, clear => 1}, 'map';
@b = watch { grep { $_ >= 4 } @a } { len => 1 }, 'grep';
is_deeply \@b, [ 4 .. 5 ], 'array: grep correctly';
@b = watch { grep { $_ >= 4 } @a } { len => 1 }, 'grep';
is_deeply \@b, [ 4 .. 5 ], 'array: grep correctly';