# First, just grab the list
if (my ($list) = $line =~ /\((\d+(?:,\d+)*)\)/) {
    # split the list by commas, assuming no whitespace
    my @list = split ',', $list;
    # initialise the magic alpha incrementer key
    my $key = 'a';
    my %hash;
    for my $value (@list) {
        next unless $value;
        $hash{$key} = $value;
        # increment magically
        ++$key;
    }
    do_something_with(%hash);
}