Perl has no Boolean type, it is interpreting values in boolean context, (which is a specialized scalar context).

There are only two default scalars 1 and ""/0 (i.e. !!1 and !!0) in case a Boolean result needs to be generated, like when using not (sic)

The extra behaviour of and/or to return the last evaluated side is closely related to short circuiting, and will by definition lead to a appropriate scalar again.

AFAIK is this feature boroughed from C, but can't be possibly extended to not or even xor

Update

That's easily proven by translating xor to a term based on and/or, since this can't be done without not

A xor B := ( A and not B) or ( B and not A)

Besides inconsistencies it's also not well defined, because the two sides of the and/or terms can be swapped (commutativity)

Cheers Rolf
(addicted to the Perl Programming Language :)
Wikisyntax for the Monastery FootballPerl is like chess, only without the dice

In reply to Re^5: 'xor' operator is not a sibling to 'or' and 'and'? by LanX
in thread 'xor' operator is not a sibling to 'or' and 'and'? by rsFalse

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.