I guess they do.

I hate being cruel... but read the parser.

Or is that also a kind of disambiguation (of the match operator)?

In one sense, those parentheses only mark the empty list, but it's probably more accurate to say that those do create a list. That's only true for the empty list however, as parsers have a very difficult time identifying invisible, non-existent characters.

Hmm.. here they obviously don't force list context?

Correct. Why would you expect them to do so? They're immaterial to the expression, just as in my $x = ( 2 + 2 );.

If parentheses did create lists, what would you expect this code to do?

my $x = ( 1 + 2 ) * 3;

Perl doesn't have a strict leftmost-applicative evaluation order, so the parentheses are necessary to disambiguate precedence.

That's the exact reason why the parentheses are necessary to group lists, but do not create lists. In:

my @fib_values = 1, 1, 2, 3;

... the expression my @fib_values = 1 is a complete expression to the parser as it is. Now it may be completely unambiguous to you that the entire expression is a list assignment, but there are plenty of more complicated assignment forms that involve mixed expressions such that Perl will give you a warning that it may have guessed wrong in this case.

Note also that you don't need parentheses when passing an argument list to a function or especially a built-in operator... again, unless you need to disambiguate something.

In reply to Re^3: (RFC) Arrays: A Tutorial/Reference by chromatic
in thread (RFC) Arrays: A Tutorial/Reference by jdporter

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • 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! —
  • 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:
    & &amp;
    < &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.