Re: xx and closures

[Eirik Berg Hanssen]

Juerd <[EMAIL PROTECTED]> writes:

> I wonder now if that can just be
>
> my $password = any('a'..'z') x 5;

  Wouldn't that generate a junction, and so need a .pick?

my $password = (any('a'..'z') x 5).pick;


  Or perhaps just leave it a junction, to use as a generator:

my $any_password = any('a'..'z') x 5;
my %password = map { $_ => $any_password.pick } @users;


  ... or am I missing something?


Eirik
-- 
Skill without imagination is craftsmanship and gives us many useful objects
such as wickerwork picnic baskets.  Imagination without skill gives us modern
art.
-- Tom Stoppard

Re: xx and closures

[Juerd]

Juerd skribis 2005-03-28 16:05 (+0200):
> In the context of x, it makes even more sense. Especially if you
> consider, for example, creating a random password:
> my $password = { any('a'..'z').pick } x 5;

I wonder now if that can just be

my $password = any('a'..'z') x 5;

(No reason to not implement the requested feature, though)


Juerd
-- 
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Re: xx and closures

[Juerd]

Luke Palmer skribis 2005-03-28  6:57 (-0700):
> We were discussing on #perl6, and thought that the feature:
> sub foo () {
> say "Blech";
> }
> { foo() } xx 5;

In the context of x, it makes even more sense. Especially if you
consider, for example, creating a random password:

my $password = { any('a'..'z').pick } x 5;

This can be done with join+map, of course, but map really isn't the
right idiom visually, because you just want the closure to be called
repeatedly, not transform a list.

For reference, this is one way to do it with join and map:

my $password = map { any('a'..'z').pick }, 1..5;

The thing that I find wrong with that is the range - 2..6 would have
accomplished the same thing. Only the 5 is important, the 1.. is not.

> Does the convenience (and obviousness when reading) enough to warrant
> adding a special case in this situation?

I certainly think so.

If a special case is not warranted, perhaps we can introduce another set
of x-ish operators, that do something special with the LHS, while x and
xx leave the LHS intact. They could be X and XX or *x and *xx, or
whatever. I'll use X and XX to demonstrate:

@foo xx 5 # [EMAIL PROTECTED], 5 times
{ foo } xx 5  # 5 times the same closure

@foo XX 5 # @foo's elements, repeated 5 times
{ foo } XX 5  # execute foo 5 times and collect its elements

IMHO, the special case is more useful, and using a temporary variable is
a good enough way to disambiguate in the rare case that you actually
want to repeat a closure. (Which with string x is even less of a
problem, because you don't often want five equal stringified closures
:).)


Juerd
-- 
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