kotlinlang #stdlib

the bodies aren't exactly equivalent either so that may create some variance depending on what mode of execution the JVM running the code is operating in

elect

03/07/2018, 10:29 AM

I'd like to have the possibility to implement the spread operator in a class

❓ 1

asad.awadia

03/07/2018, 2:10 PM

Copy code

class ListNode(var v: Int = 0) {
  var next: ListNode? = null
}

let's say we have this definition for a listNode [linkedList node] and then we do something like this to fill the list

asad.awadia

03/07/2018, 2:10 PM

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var headNode: ListNode? = null
  (1..10).forEach {
    // fill list 1 -> 2 -> 3 -> 4...-> 10
  }

  // we have lost 'pointer' to head node

asad.awadia

03/07/2018, 2:10 PM

since kotlin doesn't have 'pointers' how do you keep a copy[?] of the head node?

asad.awadia

03/07/2018, 2:11 PM

since each iteration will have a

headNode = headNode.next

marstran

03/07/2018, 2:13 PM

Use 2 variables. One for the head and one for the current node. Update only the current node.

marstran

03/07/2018, 2:13 PM

But this is off-topic for #stdlib

03/08/2018, 11:18 PM

should work fine

diesieben07

03/08/2018, 11:19 PM

Yes, that was my expectation, too 😄

holgerbrandl

03/15/2018, 1:24 PM

Why is

booleanArrayOf(true, false, false).any()

returning false? In other languages it is usually a condense method, to detect the presence of at least one

true

. Like in https://stat.ethz.ch/R-manual/R-devel/library/base/html/any.html or https://docs.scipy.org/doc/numpy/reference/generated/numpy.any.html. I know it’s because any does not work in a boolean way, but just indicating a non-empty list. Still it’s confusing.

jkbbwr

03/15/2018, 1:26 PM

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fun main(args: Array<String>) {
    println(booleanArrayOf(true, false, false).any())
}

outputs

true

holgerbrandl

03/15/2018, 1:26 PM

Stupid me. I meant

booleanArrayOf(false, false, false).any()

. Since none of them is

true

, I’d expect an

any

impl to return

false

elizarov

03/15/2018, 1:28 PM

any { it }

is what you are looking for, but a plain

any()

on a boolean array is indeed confusing. Maybe it should be deprecated with a warning…..

holgerbrandl

03/15/2018, 1:34 PM

Why is

any()

needed at all, given that there’s the semantically less confusing

isNotEmpty()

diesieben07

03/15/2018, 1:39 PM

isNotEmpty

is only declared for

Collection

, since it does not try to iterate the collection.

any

works for

Iterable

and

Sequence

, too, by trying to iterate it.

holgerbrandl

03/15/2018, 1:54 PM

any

works for all collection types, and will give the same result as

isNotEmpty

for

Collection

? If so, doesn’t this make this

isNotEmpty

obsolete/redundant?

diesieben07

03/15/2018, 1:56 PM

In theory yes, but it's much more natural to write

if (collection.isNotEmpty())

imho.

holgerbrandl

03/15/2018, 1:59 PM

Same here its a way more natural verb. But why not renaming

any

isNotEmpty

across all collection apis and getting rid of the duplicate method? As a nice side-effect this would also remove the confusion about boolean arrays.

diesieben07

03/15/2018, 1:59 PM

I agree, I have always been a bit perplexed by the parameterless version of

any

groostav

03/19/2018, 10:14 PM

its the last remaining thing that my own poorly thought out collections library has over kotlin stdlib

louiscad

03/21/2018, 1:01 PM

Why are

SortedSet

and

TreeSet

type aliases marked as internal in Kotlin 1.2.30 stdlib ?

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// also @SinceKotlin("1.1")
internal typealias SortedSet<E> = java.util.SortedSet<E>
internal typealias TreeSet<E> = java.util.TreeSet<E>

Also, the commented line is weird.

karelpeeters

03/21/2018, 1:11 PM

Maybe because there are no implementations on other platforms yet, and so they aren't really part of the stdlib yet?

louiscad

03/21/2018, 1:23 PM

Makes sense

holgerbrandl

04/04/2018, 9:21 AM

When writing own exception classes, should I inherit from kotlin.Throwable or the RuntimeException typealias? What’s benefit of using kotlin.Throwable?

karelpeeters

04/04/2018, 2:27 PM

Isn't runtime a subtype of throwable for jvm compatebility?

karelpeeters

04/04/2018, 2:53 PM

kotlin.Throwable? Where did you find that? I only see it in the native docs.

karelpeeters

04/04/2018, 2:54 PM

It's confusing because there are different ways of simplementing the exception-related classes on the different platformsz but they really do follow the Java graph:

karelpeeters

04/04/2018, 2:54 PM

@karelpeeters uploaded a file:

images(2).png▾