my @vars = do {
    my %seen;
    grep !$seen{$_}++, $bool_func =~ /([a-zA-Z]\w*)/g;
};

##</code><code>##

for my $assignment ( 0 .. (2**@vars)-1 ) {
    my %val;

    $val{$vars[$_]} = ( $assignment >> $_ ) & 1
        for 0 .. $#vars;
.........