Then you do need the initialization. You could write something along the lines of 

for my $a (@members) {
    for my $b (@memebers) {
         $overlap->{$a}{$b} = 0;
    }
}

[download]

before the other loop.

Perl 6 - second systems done right

In reply to Re^5: how to set a value for a hash reference by moritz
in thread how to set a value for a hash reference by AWallBuilder

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