in reply to Re^2: A "but" operator.
in thread A "but" operator.
you say "but" is just like "and". How's that possible?
In fact, some languages have words that can be
translated into English as either "but" or "and".
For example, the Greek postpositive "de" (delta
epsilon) is most frequently translated into English
as "but", but it can also be translated into English
as "and" (though for "and" the conjunction "kai" is
much more common).</philolophile>
The meaning of "but" and "and" in English _is_
different, but the difference doesn't have very much
to do with the meaning of "and" in Perl. The real
difference is that "but" implies that the second
item may be surprising given the first, while "and"
has only the more basic meaning of conjunction.
Still, in terms of their value as boolean operators,
both would mean the same thing: the first argument
is true; the second argument is also true. Boolean
logic doesn't much care about surprise value. Think
about the difference in meaning between "The ball is
blue and it is also heavy" versus "The ball is blue
but it is also heavy". In both cases we're dealing
with a heavy blue ball, but in the latter case there
is an implication (quite a surreal one, given the
usual presumption that color and weight are pretty
much orthogonal) that we might ordinarily expect a
blue ball not to be heavy -- but this one is.
And, as pointed out, the word "but" is going to be
used in Perl6 for something really cool that will
be sure not to disappoint you, though not as a
my $x = ("The answer to the ultimate question of life, the universe
+, and everything" but 42 but false but undef);
print "Number: " . (0+$x) . "\n";
print "String: " . $x . "\n";
print "Boolean: false\n" unless $x;
print "Undefined" if not defined $x;
(I might have some legacy Perl5 syntax in there by
mistake. For some reason, though I want to learn
and use Perl6, I keep finding myself being lured
away by Perl5 and its persistent siren call of
actually being ready for use now.)
"In adjectives, with the addition of inflectional endings, a changeable long vowel (Qamets or Tsere) in an open, propretonic syllable will reduce to Vocal Shewa. This type of change occurs when the open, pretonic syllable of the masculine singular adjective becomes propretonic with the addition of inflectional endings."
— Pratico & Van Pelt, BBHG, p68