Yeah, I tried a couple zip-based variants, but thought the flattening
was a little confusing when combined with the reversal (so keys and
values get swapped when the list is reversed). I'd forgotten about
the ^max shorthand, though. Thanks for the reminder.
So how to loop over a list of sublists one at a time, passing each
item to a sub of arity > 1, automatically expanding each item into
separate parameters? Ruby does it automatically based on arity, but
Ruby doesn't support loop-by-n-at-a-time, so there's no conflict...
On 12/25/08, Patrick R. Michaud <pmich...@pobox.com> wrote:
> On Thu, Dec 25, 2008 at 12:39:24PM -0500, Mark J. Reed wrote:
>> On Thu, Dec 25, 2008 at 12:00 PM, Patrick R. Michaud <pmich...@pobox.com>
>> wrote:
>> > On Thu, Dec 25, 2008 at 12:53:06AM -0500, Mark J. Reed wrote:
>> >> I also tried this, but it caused Rakudo to throw a StopIteration and
>> >> then segfault:
>> >>
>> >> for [...@gifts[0..$day-1]].pairs.reverse -> $n, $g
>> >
>> > The StopIteration occurs when there aren't enough elements in the
>> > list to supply to the parameters to the body. In the example above,
>> > it would occur whenever there are an odd number of pairs.
>>
>> OK, so that loops through the list in groups of two. So how do I Ioop
>> through a list of Pairs assigning the key to one var and the value to
>> another? It's not a Hash, and calling .kv on it yields 0=>first pair,
>> 1=>second pair, etc... I don't want to Hashify it because I want to
>> preserve the order...
>
> Extracting the keys+values from a list of Pairs was a question that
> occurred to me as well when implementing it... I don't know the answer
> to that.
>
> However, for this specific problem, perhaps the zip operator is a
> better choice anyway:
>
> for (^$day Z @gifts).reverse -> $g, $n { ... }
>
> I'm not entirely sure of the order of the $g, $n arguments here,
> or exactly how .reverse chooses to change the order of the items
> produced by infix:<Z> (does it flatten or no?). But some permutation
> of this should work.
>
> Pm
>
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Mark J. Reed <markjr...@gmail.com>
