Perl6 Rule of Comma

ruleofcomma

                                           < Is there a top-level comma? >
                               YES                                                NO
               < Are you in flattening context? >         < Does the destination bind to a $ or unsigilled? >
               YES                            NO                   YES                            NO
<protected by .item or $() ?>          Stays the same        Stays the same                  Decontainerize
   YES                   NO
Stays the same       Interpolate


$_ for flat 1, $[2,3];     # YES, YES, YES: 1, [2,3]
$_ for flat 1, [2,3];      # YES, YES, NO: 1,2,3
$_ for flat [2,3],;        # YES, YES, NO: 2,3
$_ for flat 1, [2,3];      # YES, YES, NO: 1,2,3
$_ for 1,[2,3];            # YES, NO:      1,[2,3]
my $a = [2,3];             # NO, YES:      [2,3]
my \a = [2,3];             # NO, YES:      [2,3]
$_ for flat = [2,3];       # NO, NO:       2,3

# Assuming list assignment still flattens, which apparently is still TBD:
my @a = [2,3];         # NO, NO:       2,3
my @a = [2,3],;        # YES, YES, NO: 2,3
my @a = 1, $[2,3];     # YES, YES, YES: 1, [2,3]
my @a = 1, [2,3];      # YES, YES, NO: 1,2,3