Channels
#stdlib
- m
mg6maciej
03/31/2017, 10:00 AMThis pattern repeats in my code... I guess there is nothing in #stdlib for this, so It's more of a question about good name:Copy codeval (first4, fifthAndBeyond) = list.takeAndDrop(4) - e
enleur
03/31/2017, 10:08 AMlooks like partition➕ 1 - e
enleur
03/31/2017, 10:11 AM - m
mg6maciej
03/31/2017, 10:12 AMIt's not. I don't have predicate there. I could do predicate on indexes 😉 - m
mg6maciej
03/31/2017, 10:13 AMlist.withIndex().partition { it.index < 4 }.map { it.value } - m
mg6maciej
03/31/2017, 10:14 AMThis would be an implementation of my function using
, but I just want to usepartition
andtake
inside.drop - e
enleur
03/31/2017, 10:14 AMit should beCopy codeval (first4, fifthAndBeyond) = list.withIndex().partition { it.index < 4 } - m
mg6maciej
03/31/2017, 10:15 AMOh, yeah.
returnspartition
, so I can't map on it.Pair - m
mg6maciej
03/31/2017, 10:16 AMI have found Scala calls this
, so I'll go with this name.splitAt - m
mg6maciej
03/31/2017, 11:00 AMJust for completeness:Copy code
Maybe it will appear in #stdlib some day.fun <T> List<T>.splitAt(index: Int) = Pair(take(index), drop(index))👍 1 - k
kirillrakhman
03/31/2017, 11:47 AM@mg6maciej out of curiosity, what is you use case? - m
mg6maciej
03/31/2017, 11:47 AMFor using
?splitAt - k
kirillrakhman
03/31/2017, 11:47 AMyes - m
mg6maciej
03/31/2017, 11:48 AMI have decks of cards and players draw some. Usually it's 1, but on special occasions more. - m
mg6maciej
03/31/2017, 11:49 AMSo it looks like this:val (receivedItems, newItems) = items.splitAt(receivedItemsCount) - m
mg6maciej
03/31/2017, 11:50 AMThe whole thing is immutable, that's why there is
and at the end I return a copy:newItemsreturn copy(..., items = newItems) - k
kirillrakhman
03/31/2017, 11:50 AMcool 👍 - m
mg6maciej
03/31/2017, 11:53 AMI was using
andtake
before refactoring, but I didn't like how it wasn't DRY. In this example there isdrop
variable, but in most places it wasreceivedItemsCount
or1
. And I got that constant twice in a block of code.5 - k
kirillrakhman
03/31/2017, 11:54 AMyou're right - k
kirillrakhman
03/31/2017, 11:54 AMthe only thing bugging me is how it wastes allocations - k
kirillrakhman
03/31/2017, 11:54 AMbut I guess there's little you can do without valhalla - m
mg6maciej
03/31/2017, 11:54 AMOh, yeah. Not too much worries, cause this code is on the server, but I already changed it to: - m
mg6maciej
03/31/2017, 11:55 AMCopy codefun <T> List<T>.splitAt(index: Int) = Pair(subList(0, index), subList(index, size))👍 1 - k
kirillrakhman
03/31/2017, 11:55 AMalso, hotspot might be able to elide the allocations, but you never know - m
mg6maciej
03/31/2017, 11:56 AMI don't care for now. It will not have more than 100 users at the same time. - k
kirillrakhman
03/31/2017, 11:56 AMright. most of the time, I'm just pedantic with allocations for no good reason - s
sreich
03/31/2017, 12:40 PMBecause dalvik has traumatized you with fear of allocations - k
kirillrakhman
03/31/2017, 12:40 PMbasicly - m
mg6maciej
03/31/2017, 1:06 PMOr Google's #perfmatters hashtag. - a
aleix
03/31/2017, 1:09 PM@aleix has left the channel