Re: Conditionally included list elements
* Juerd [EMAIL PROTECTED] [2006-06-18 14:10]:
pugs my @foo = 1, 2, 3, { 4 if 0 }.(), 5; say @foo.perl
[1, 2, 3, 5]
bool::true
pugs my @foo = 1, 2, 3, { 4 if 1 }.(), 5; say @foo.perl
[1, 2, 3, 4, 5]
bool::true
That’s “conceptually noisy” though… I don’t know if I’d end up
picking
$foo, $bar, { $baz if $wibble }.(), $quux
over
$foo, $bar, ( $wibble ?? $baz !! () ), $quux
With more complex “movable parts,” there would be even less
difference between the two than here.
Does Perl 6 have `do BLOCK` like Perl 5? That would make it
$foo, $bar, do { $baz if $wibble }, $quux
which I find more acceptable.
Regards,
--
#Aristotle
*AUTOLOAD=*_;sub _{s/(.*)::(.*)/print$2,(,$\/, )[defined wantarray]/e;$1};
Just-another-Perl-hacker;
Re: Conditionally included list elements
Hi Stuart,
* Stuart Cook [EMAIL PROTECTED] [2006-06-18 15:05]:
On 6/18/06, A. Pagaltzis [EMAIL PROTECTED] wrote:
Is there a construct in Perl 6 to express this more
immediately? Something along the lines of the following would
seem ideal:
$foo, $bar, ( $baz if $wibble ), $quux
How about this:
pugs sub infix:pv($x, $cond) { $cond ?? ($x,) !! () }; say 1, 2, (3 pv
1), 4
1234
bool::true
Good point! I like.
However, what are the evaluation semantics here? Neither the
ternary nor the `if`-based solutions evaluate the expression they
return if the condition turns out to be false. Wouldn’t your
solution evaluate it unconditionally?
Regards,
--
Aristotle Pagaltzis // http://plasmasturm.org/
Re: Conditionally included list elements
On Sun, Jun 18, 2006 at 05:18:14PM +0200, A. Pagaltzis wrote:
pugs sub infix:pv($x, $cond) { $cond ?? ($x,) !! () }; say 1, 2, (3 pv
1), 4
However, what are the evaluation semantics here? Neither the
ternary nor the `if`-based solutions evaluate the expression they
return if the condition turns out to be false. Wouldn’t your
solution evaluate it unconditionally?
That can be solved with an explicit thunk:
sub infix:pv1 ($x, $cond) { $cond ?? ($x(),) !! () }; say 1, 2, {3} pv 1, 4
Or maybe 'is lazy' on $x?
--
Gaal Yahas [EMAIL PROTECTED]
http://gaal.livejournal.com/
Re: Conditionally included list elements
On Sun, Jun 18, 2006 at 05:18:52PM +0200, A. Pagaltzis wrote: : Maybe TheLarry can enlighten us… :-) We already have the operator you want. It's spelled Cxx?. :-) Larry
Re: Conditionally included list elements
* Larry Wall [EMAIL PROTECTED] [2006-06-18 19:05]:
On Sun, Jun 18, 2006 at 05:18:52PM +0200, A. Pagaltzis wrote:
: Maybe TheLarry can enlighten us… :-)
We already have the operator you want. It's spelled Cxx?. :-)
Nice. :-) How’s it used? S03 doesn’t list it.
Regards,
--
#Aristotle
*AUTOLOAD=*_;sub _{s/(.*)::(.*)/print$2,(,$\/, )[defined wantarray]/e;$1};
Just-another-Perl-hacker;
Re: Conditionally included list elements
On Sun, Jun 18, 2006 at 07:27:57PM +0200, A. Pagaltzis wrote: : * Larry Wall [EMAIL PROTECTED] [2006-06-18 19:05]: : On Sun, Jun 18, 2006 at 05:18:52PM +0200, A. Pagaltzis wrote: : : Maybe TheLarry can enlighten us… :-) : : We already have the operator you want. It's spelled Cxx?. :-) : : Nice. :-) How’s it used? S03 doesn’t list it. Nope. Doesn't list the C**- or C||! operators either. :-) (Hint: it doesn't matter if you put a space between the Cxx and the C?.) Larry
Re: Conditionally included list elements
* Larry Wall [EMAIL PROTECTED] [2006-06-18 19:40]:
On Sun, Jun 18, 2006 at 07:27:57PM +0200, A. Pagaltzis wrote:
* Larry Wall [EMAIL PROTECTED] [2006-06-18 19:05]:
We already have the operator you want. It's spelled Cxx?.
:-)
Nice. :-) How’s it used? S03 doesn’t list it.
Nope. Doesn't list the C**- or C||! operators either. :-)
(Hint: it doesn't matter if you put a space between the Cxx
and the C?.)
Ahh. So you’re telling me that Perl 5 has the same operator, but
it spells it Cx!!. Clever!
Regards,
--
#Aristotle
*AUTOLOAD=*_;sub _{s/(.*)::(.*)/print$2,(,$\/, )[defined wantarray]/e;$1};
Just-another-Perl-hacker;
