Also note that "scalar" can internally be a real, integer, string, reference or undef or a combination of (some of) those + magic (like blessedness).

my $regex = qr/x/;
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I know $regex is a scalar, but the thing it refers to should be considered another type (which ref calls "Regexp").

That's interesting. Perhaps, basically, it's whether or not one of the types above are blessed? Otherwise any blessed scalar is another type? That also makes me wonder if we could count iterators somehow.

-Paul

Otherwise any blessed scalar is another type?

I tend to think that a scalar has a reference to a blessed thing rather than the scalar itself being blessed.

my $unblessed = {};
my $blessed = $unblessed;
bless $blessed, 'Holy::Holy';
printf "%s\n%s\n", ref $unblessed, ref $blessed;
__END__
Holy::Holy
Holy::Holy
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That's just a nitpick, though.

I ordinarily wouldn't think of some user-created object as being a separate data type except that they can be overloaded to act just like one. Where does something like Math::BigInt fit in? I think this is a point on which reasonable people can disagree.

That also makes me wonder if we could count iterators somehow.

I don't know what you mean by this.

I know $regex is a scalar, but the thing it refers to should be considered another type (which ref calls "Regexp").

(Sorry for replying so late!) Indeed the return value of qr is a blessed reference. Thus these "objects" are real objects, and turn out to be autoboxed:

use YAPE::Regex::Explain;

sub Regexp::explain {
    print YAPE::Regex::Explain->new(shift)->explain;
}

qr/^.*?Foo(Bar){3,7}\d+/->explain;
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In Perl 6 everything is an object too, but currently this is not the case for simple scalars, arrays, etc. unless you use the very interesting autobox module, which used to require a patch, but doesn't anymore, last I checked.

Do you want to count 'constant' (provided by use constant), or is that some sort of scalar?

How about a heredoc? Does the entity following __DATA__ or __END__ have a data type?

Is a list a distinct type from an array?

My take:

constants are subroutines returning (lists of) scalars.

heredocs are plain strings. they just have a different syntax from "normal" quoted strings.

Everything after (and before) __DATA__ / __END__ is in a file, but everything after __DATA__ or __END__ is not processed until read (via the DATA filehandle, or by opening and reading __FILE__), so it's not perl data.

A list differs from an array. I'm not sure if you can call a list a data type, in perl, though.

"What should it profit a man, if he should win a flame war, yet lose his cool?"

Contextual::Return