p6.p6

class CardWorks1 {
    # subset's block uses { ... } instead of WhateverCode
    my @faces = <2 3 4 5 6 7 8 9 10 Jack Queen King Ace>;
    subset Face of Str where { $_ eq @faces.any };
    has Face  $.face  is required;
}
class CardWorks2 {
    # Array is assigned to in a BEGIN
    BEGIN my @faces = <2 3 4 5 6 7 8 9 10 Jack Queen King Ace>;
    subset Face of Str where * eq @faces.any;
    has Face  $.face  is required;
}
class CardBroken {
    # if change @faces.say; we'll see array is empty during the check
    my @faces = <2 3 4 5 6 7 8 9 10 Jack Queen King Ace>;
    subset Face of Str where * eq @faces.any;
    has Face  $.face  is required;
}
dd CardWorks1.new: :face<2>; # Success
dd CardWorks2.new: :face<2>; # Success
dd CardBroken.new: :face<2>; # Type check fail