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#stdlib
- k
kirillrakhman
08/16/2016, 5:49 PMI think it's gone after restarting - v
voddan
08/16/2016, 5:51 PMAfaik there are no way to spoil stdlib functions with incremental anyways - d
dimsuz
08/16/2016, 6:21 PMCopy code
is there a nice way of having it converted to a corresponding String if it's not null and keeping null if it's null?val n: Int? = null n.toString() => "null" - d
dimsuz
08/16/2016, 6:22 PM
- would always convert to stringn ?: "" - i
ilya.gorbunov
08/16/2016, 6:22 PMn?.toString() - d
dimsuz
08/16/2016, 6:23 PMhmm. that crossed my mind but i somhow thought it would be the same as "n.toString()" - d
dimsuz
08/16/2016, 6:23 PMbecause "toString: Any? -> String" - d
dimsuz
08/16/2016, 6:24 PMso compiler will respect my wish in this case? 🙂 - i
ilya.gorbunov
08/16/2016, 6:30 PMsafe call always verifies if the receiver is null first, and then only if it's not invokes member - d
dimsuz
08/16/2016, 6:34 PMthanks, good to know! - n
nhaarman
08/17/2016, 2:17 PMIs there something like this in the stdlib?Copy codeinline fun <T, reified R : T> Collection<T>.filterInstanceOf() = filter { it is R }.map { it as R } - y
yole
08/17/2016, 2:18 PMfilterIsInstance - n
nhaarman
08/17/2016, 2:18 PMReally? - n
nhaarman
08/17/2016, 2:18 PMHow could I miss that - d
dimsuz
08/17/2016, 2:28 PManother "is there" question 🙂 is there something like
I.e. filter map entries and get a value of first entry which matchedMap<K,V>.first { (entry) -> Boolean } : V - y
yole
08/17/2016, 2:31 PMmap.entries.first { … } - d
dimsuz
08/17/2016, 3:04 PMface-🌴 - d
dimsuz
08/17/2016, 3:04 PMthanks - d
dimsuz
08/18/2016, 1:30 PMhmm. is there an stdlib function to do a magic flip
?Map<K,V> -> Map<V,K> - d
dimsuz
08/18/2016, 1:35 PMfor now did it like this
, don't know if this is the best solutionmap.asSequence().associateTo(hashMapOf(), { it.value to it.key }) - o
orangy
08/18/2016, 1:37 PMWas recently.map.entries.associateBy({it.value}, {it.key}) - d
dimsuz
08/18/2016, 1:38 PMthanks! - b
bamdmux
08/26/2016, 7:04 AMComing from a discussion in #getting-started Is there a way to split collections in chunks of a predefined length? - b
bamdmux
08/26/2016, 7:04 AMSomething "cleaner" thanfun <T> Collection<T>.split(n: Int=2) = withIndex().groupBy { (it.index/n) }.values.map{it.map { it.value }} - b
bamdmux
08/26/2016, 7:09 AMAnd/or more efficient - v
voddan
08/26/2016, 8:23 AM - d
dimsuz
08/26/2016, 3:41 PMWhen I have List<ObjectWithId> and List<String> (list of ids) and I want to filter first list to contain only entries with id in a second list, I do something likeCopy code
is this a good approach or is there something more concise/faster? I do this so often that I sometimes think there's some idiom for this, is there?list1.filter({ listOfIds.contains(it.id) }) - y
yole
08/26/2016, 3:42 PM - y
yole
08/26/2016, 3:43 PM(well, almost) - d
dimsuz
08/26/2016, 3:43 PMhah, and I tried searching for something likedifference