How to learn Perl has been an eternal problem for the Perl community. Compared to many other languages that place an emphasis on teaching the basics and using education as a tool for evangelism we've had sporadic efforts along those lines. Given the size of our community and the fact that the best programmers are often in great demand, we have a hard time pumping out the needed docs and examples.

I've been using ChatGPT quite a lot lately and find that although it makes some mistakes it actually churns out pretty decent Perl if given good instructions. For example here's one I did this AM. We just had the dreaded hour shift here in the US and I'm just not up to thinking so I asked Chat GPT:

"write a perl subroutine that accepts two hashrefs and a list. For each item in the item merge the hashrefs by combining the values into an array ref. "

Here's what it pumped out:

sub merge_hashes {
    my ($hashref1, $hashref2, @list) = @_;

    foreach my $item (@list) {
        my @values = ();

        if (exists $hashref1->{$item}) {
            push @values, @{$hashref1->{$item}};
        }

        if (exists $hashref2->{$item}) {
            push @values, @{$hashref2->{$item}};
        }

        $hashref1->{$item} = \@values;
    }
}

Along with the following explanation:

"In this subroutine, we first receive two hashrefs and a list as input. We then iterate over each item in the list and create an empty array to hold the merged values.

We then check if each hashref has a value for the current item. If so, we push all the values for that item into the @values array. We then assign the merged @values array as the value for the current item in the first hashref.

Finally, we return the updated first hashref after all items have been processed.

Note: The original hashref1 is modified in place by this subroutine."

Not too bad. I than asked it to modify the code thus:

"change the subroutine so that the item value can be either a scalar or an array ref. we should normalize all values to arrayref"

And it came up with this:

sub merge_hashes {
    my ($hashref1, $hashref2, @list) = @_;

    foreach my $item (@list) {
        my @values = ();

        # Check if the item value is an array ref or scalar
        if (ref $hashref1->{$item} eq 'ARRAY') {
            push @values, @{$hashref1->{$item}};
        } elsif (defined $hashref1->{$item}) {
            push @values, $hashref1->{$item};
        }

        if (ref $hashref2->{$item} eq 'ARRAY') {
            push @values, @{$hashref2->{$item}};
        } elsif (defined $hashref2->{$item}) {
            push @values, $hashref2->{$item};
        }

        # Normalize the value to an array ref
        $hashref1->{$item} = scalar @values > 1 ? \@values : $values[0] || [];
    }
}

Lastly I asked:

"fix this so that the $item value is undefined we don't get an error"

And it produced:

Although its far from perfect this is a space we should be watching and toying with since it seems to me to be a possible way to help bootstrap programmers that need to or want to get into Perl but are not finding the existing learning and mentoring capacity sufficient.