kotlinlang #announcements

So it's not like there is a single integer for the recursion limit, it'll depend on how much space a stack frame takes up for your particular function.

warriorprincess

06/01/2018, 11:00 AM

does

minBy

actually give a reference to original object? I do

lowest = lowest?.next

in my code above, does it actually move the

head

of the list stored in

lists

aandreyev

06/01/2018, 12:21 PM

Hello I am trying to use micronaut but cannot debug tests in IDEA Seems like the issue is related to kapt annotation processing. https://stackoverflow.com/questions/50642455/kotlin-micronaut-testng-test-fails-in-idea-but-pass-via-gradle Is there any config trick or workaround?

Fuyang

06/01/2018, 1:23 PM

Maybe someone here can help me with this how to stop

null

get into map values from json string? https://stackoverflow.com/questions/50643864/kotlin-how-to-prevent-null-gets-into-map-object-during-jackson-json-deserializ Much appreciated 🙂

selva

06/01/2018, 2:31 PM

Hi Friends, I am upgrading kotlin from 0.9.223 to 1.2.31. After upgrade i am getting an error since kotlin-time split into stdlib and stdlib-js. There is shared code used in JVM and JS modules. But having problem with compiling Date dataype. Since kotlin.js.Date works JS module and java.util.Date works in JVM module. can anyone please help me on this ? Thanks Selva

warriorprincess

06/01/2018, 7:27 PM

Copy code

fun mergeKLists(lists: Array<ListNode?>): ListNode? {
        var holder: List<ListNode?> = arrayListOf()
        while (true) {
            val bulk = lists.withIndex().minBy { (_, value) -> value?.`val` ?: Int.MAX_VALUE }
            val index = bulk?.component1(); val lowest = bulk?.component2() ?: break
            holder += lowest
            lists[index!!] = lists[index]?.next
        }
        for (index in 1 until holder.size) holder[index-1]?.next = holder[index]
        return if (holder.isNotEmpty()) holder[0] else null
    }

warriorprincess

06/01/2018, 7:28 PM

guys any comments on code quality and style? Am I using any kotlin features in a way not recommended?

Roman Dzhadan

06/02/2018, 9:30 AM

Hey guys! I'm trying to upgrade my microservices up to JVM 10. Latest maven plugin says:

org.jetbrains.kotlin:kotlin-maven-plugin:1.2.41

Unknown JVM target version: 10. Supported versions: 1.6, 1.8

Is there any chance to run JVM 10 with Kotlin 1.2?

kenkyee

06/02/2018, 9:40 AM

Change your jvm so it targets java 1.8 byte code...

Hamza

06/02/2018, 10:42 AM

No channel for javalin? 🤔

karelpeeters

06/02/2018, 2:06 PM

Someone did a while ago:

#33244c,#423393,#944c94,#FFFFFF,#423393,#FFFFFF,#944C94,#F88909

thomasnield

06/02/2018, 6:18 PM

Stack overflows aside, my question is this: can recursion inside a

Sequence

flatMap()

be bad for performance when you need to recurse a larger number of items (e.g. 1000, 10000)? Should I be doing a loop with

tailrecur

instead?

coder82

06/02/2018, 10:22 PM

is there a coroutine primitive which waits for a flag to be set?

mik_os

06/03/2018, 7:25 PM

Hi, I have a question about Kotlin compiler performance. My project (Android app) have next stats:

Copy code

-------------------
Language       code
-------------------
Java          42659
Kotlin         8834

Task

compile<Flavor>Kotlin

takes 25s Task

compile<Flavor>JavaWithJavac

takes 8s Is this something I should report to bugtracker? Or 14x (3x more time for 4.6x less code) slower kotlin compilation have some reasonable explanation?

tschuchort

06/03/2018, 8:58 PM

is there any way to get a reference to a property? I can do this:

fun <T> foo(t: T, setProp: T.(Int) -> Unit, getProp: T.() -> Int) = t.apply { setProp(getProp() + 1) }

but what I want to do is:

fun <T> foo(t: T, prop: Property<T,Int>) = t.apply { prop += 1 }

lawlorslaw

06/04/2018, 8:40 AM

The

kotlin-koans

repo is the problem. Every time you make a change to a test you have to rerun the

testClasses

Gradle task.

karelpeeters

06/04/2018, 9:00 AM

(with large constant factors because all of the lists beging created)

Benoit Duffez

06/04/2018, 11:41 AM

Hello. I have a class (let's call it

Entity

) that is inherited from two children, and they need to change the type of one property. This is because these classes are used to retrieve data from a backend (in serialized in JSON, deserialized with Gson). In fact, the server uses the same object for downlink (e.g.

GET /x/y/z.json

returns a list of

Entity

) and uplink (

POST /abc

with one

Entity

in the body), but one of the fields has not the same type whether it's uplink or downlink (bummer... I can't change the server code...). So in

Entity

i have declared the property as

open var stuff: Any? = null

, and I expected the

EntityUplink

for example to have

override var stuff: ActualType? = null

but the compiler refuses that. Is that a violation of the language (e.g. not possible/not designed to do that) or am I missing something?

BorzdeG

06/04/2018, 3:23 PM

Prompt, how to receive in a method “getProperty” a field name?

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abstract class DemoSuper() {
  protected fun getProperty(defaultValue: String): String {
    // field name?
    return defaultValue
  }
}

class Demo : DemoSuper() {
  val f0: String by lazy { getProperty("f0") }
  val f1: String by lazy { getProperty("f1") }
}

karelpeeters

06/05/2018, 9:57 AM

Sure,

property.returnType

edwardwongtl

06/05/2018, 10:15 AM

I think it more about compiler trick for this to work

tschuchort

06/05/2018, 10:18 AM

meanwhile you can use an epimorphism to lift any

Killer -> A

function to a

Test -> A

function but it's somewhat annoying to use

nwh

06/05/2018, 1:14 PM

Is there a way to hook into a data class' copy method? For example:

Copy code

data class Example(val name: String?)

Let's say I have an

Example("")

, but I want blank strings to be null. I can do:

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ex.copy(name = if (name.isBlankOrNull()) null else name)

But this requires hard coding. Is there a safe way to process all the fields like this?

gyl

06/05/2018, 3:36 PM

Hello everyone, Did someone managed to unit test

object

classes ? We would like, for each test, re init a

lateinit var foo

property with different values a on our singleton, but actually, once it is initialized once, we found no way to reinit the singleton. Sorry for my english..

bdawg.io

06/05/2018, 4:39 PM

Is there a fundamental difference between

IntArray

and

Array<Int>

? If so, is there a reason why the compiler doesn’t treat them as type aliases?

adams2

06/05/2018, 6:17 PM

recommendations for avoiding an NPE on line 15?

Seri

06/05/2018, 8:43 PM

I love that font

jmccance

06/05/2018, 8:50 PM

His take was “If I have an

and call

copy

, I expect to be able to call the same functions on the copy as I could on

.”

david-wg2

06/06/2018, 8:44 AM

anyone here have experience with bazel (https://bazel.build/)?

Andrei

06/06/2018, 9:09 AM

So it's a bad a idea to chain such deconstructive methods together?