Another way to look at it is to realize that in Perl, different basic types can have the same name. There has to be some way to distinguish between, e.g., a hash and a scalar containing a hash reference. The  -> (arrow) operator (see perlop) makes this syntactic distinction, as it were. Below the top level, nested hashes (and arrays) can only be references, so the compiler does not need an arrow operator for disambiguation (but an  -> can always be used at lower level(s) if you wish).

c:\@Work\Perl\monks>perl -wMstrict -le
"my %hash = ( 'structure' => { 'uses plain sigil'  => 'dereference' } 
+);
 my $hash = { 'reference' => { 'needs -> operator' => 'at top'      } 
+};
 ;;
 print $hash    {'structure'}{'uses plain sigil' };
 print $hash -> {'reference'}{'needs -> operator'};
"
dereference
at top
[download]

See also The Perl Data Structures Cookbook.

---

---

Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!

Titles consisting of a single word are discouraged, and in most cases are disallowed outright.

Read Where should I post X? if you're not absolutely sure you're posting in the right place.

Please read these before you post! —

• How do I compose an effective node title?
• How do I post a question effectively?
• Markup in the Monastery

Posts may use any of the Perl Monks Approved HTML tags:

a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr

You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)

	For:		Use:
	&		&
	<		&lt;
	>		&gt;
	[		&#91;
	]		&#93;

Link using PerlMonks shortcuts! What shortcuts can I use for linking?

See Writeup Formatting Tips and other pages linked from there for more info.