The C<< => >> operator is a synonym for the comma, but forces any word
(consisting entirely of word characters) to its left to be interpreted
-as a string (as of 5.001). If the argument on the left is not a word,
-it is first interpreted as an expression, and then the string value of
-that is used.
+as a string (as of 5.001). This includes words that might otherwise be
+considered a constant or function call.
+
+ use constant FOO => "something";
+
+ my %h = ( FOO => 23 );
+
+is equivalent to:
+
+ my %h = ("FOO", 23);
+
+It is I<NOT>:
+
+ my %h = ("something", 23);
+
+If the argument on the left is not a word, it is first interpreted as
+an expression, and then the string value of that is used.
The C<< => >> operator is helpful in documenting the correspondence
between keys and values in hashes, and other paired elements in lists.
+ %hash = ( $key => $value );
+ login( $username => $password );
+
=head2 List Operators (Rightward)
On the right side of a list operator, it has very low precedence,