kotlinlang #announcements

runBlocking {

      val timer = measureTimeMillis { delay(1000) }
      println("Delay Measure: $timer")

      val timer2 = measureTimeMillis { Thread.sleep(1000) }
      println("Thread Sleep Measure: $timer2")

    }

but the result was unexpected for me:

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Delay Measure: 1064
Thread Sleep Measure: 1002

Is it something I should expect the

delay

in coroutine takes more time than the

Thread.sleep

jcechace

11/05/2018, 12:41 PM

Any idea how to write this piece of code nicer?

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override fun checkServerTrusted(chain: Array<out X509Certificate>?, authType: String?) {
        try {
            customTm?.checkServerTrusted(chain, authType) ?: defaultTm.checkServerTrusted(chain, authType)
        } catch (e : CertificateException) {
            defaultTm.checkServerTrusted(chain, authType)
        }
    }

arve

11/05/2018, 1:33 PM

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val input: List<List<Double>> = 
 [[1, 2, 3 (....)],
  [4, 5, 6, (...)],
  [7, 8, 9, (...)]] 
val expected= [12, 15, 18, (...)]

Trying to find an elegant way to sum elements of a list of list of numbers by index (i.e. "downwards")🤔

diesieben07

11/05/2018, 1:34 PM

input.map { it.sum() }

🚫 1

DJ Mitchell

11/05/2018, 4:01 PM

Hi 👋 I'm coming from the Swift world and there are a set of protocols over there that called

ExpressibleByXXXXLiteral

, so you can create a type and if you pass the correct type of literal as an argument the compiler will automatically lift that literal into the correct type. For instance one nice thing in Kotlin would be to be able to express an

inline class

as a literal without having to explicitly initialize a type at the callsite:

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inline class UserID(val value: Int) {}

data class User(val userID: UserID) {}

// would love to be able to do this
val user = User(5)

// instead i have to do this
val user = User(UserID(5))

gsala

11/05/2018, 4:05 PM

doesn't that miss the point of the inline class though? If

User

requires a

UserID

to be constructed, it shouldn't be allowed to be constructed with any

Int

🧵 2

John Dengis

11/05/2018, 6:03 PM

Hey, I was using Kotlin with a couple of Java libraries and encounter an internal compiler error when working with inheritance and a few different types of annotations. What is the process to go through for filing compiler bug reports? I went to the Kotlin YouTrack site, but couldn't find where to submit a new issue.

pavel

11/06/2018, 12:07 AM

So I have a piece of code that looks like this:

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val foo = listOf("foo", "bar", null, "")
    val bar = foo.filter { !it.isNullOrEmpty() }

the compiler is arguing that

bar

List<String?>

while my position is that it should be

List<String>

. Am I expecting too much from contracts? And is there a better way to write this?

christophsturm

11/06/2018, 9:24 AM

is there a kotlin lib that will fill data objects with random data for testing? something like https://github.com/topicusoverheid/java-factory-bot

elect

11/06/2018, 10:16 AM

I can see (by the `println`s in console) that my

lazy

is actually being executed twice: https://github.com/kotlin-graphics/uno-sdk/blob/master/src/main/kotlin/uno/awt/JawtDemo.kt#L79-L84

elect

11/06/2018, 10:17 AM

how is that possible? Ps: calling it from java

APXEOLOG

11/06/2018, 1:38 PM

Guys what library do you use for json object mapping? I'm using

jackson-module-kotlin

for now, but i face some issues there with kotlin support. Maybe there are some other simple to use and easily customisable solutions

vibin

11/06/2018, 2:46 PM

Screenshot 2018-11-06 at 8.14.57 PM.png

pawel.urban

11/06/2018, 3:45 PM

Is there any neat way of doing

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private val _title = BehaviorRelay.create<String>()
    val title: Observable<String> = _title

without the backing property?

🧵 1

dave08

11/06/2018, 4:15 PM

Say I have a

val someSet: Set<String>? = setOf("this", "that", "this=3")

and I'd like to extract the 3 as an

Int

, is this the most ideomatic/efficient way to do it?

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someSet?.firstOrNull { it.startsWith("this=") }
					?.substringAfter("this=")
					?.toInt() ?: 0

coder82

11/06/2018, 4:35 PM

can_I_use_a_wildcard_for_websocket_routes_.js

miha-x64

11/06/2018, 5:31 PM

Are there any ways to achieve exhaustiveness, but enums or sealed classes? I have a bunch of objects and want to provide each of them with some data. (Certainly, I've got DTO schema and want to add platform-specific (SQL-specific, JSON-specific, etc) metadata)

breun

11/06/2018, 9:04 PM

The context for me would be a server application serving API calls.

stkent

11/06/2018, 9:31 PM

I'm trying to build a Kotlin version of the lazy prime number generator based on the Sieve of Eratosthenes from this Haskell video (10m55s):

https://www.youtube.com/watch?v=bnRNiE_OVWA&t=10m55s▾

I ended up here:

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fun sieve(remainderSequence: Sequence<Int> = generateSequence(2) { it + 1 }): Sequence<Int> {
    val newPrime = remainderSequence.first()
    val newRemainderSequence = remainderSequence.filterNot { it % newPrime == 0 }

    return sequence {
        yield(newPrime)
    }.plus(sieve(newRemainderSequence))
}

which I thought would remain lazy, but it appears not to. What am I missing?

tateisu

11/07/2018, 1:54 AM

Auto format does bit strange indent. Is there settings to fix it?

Zaidi

11/07/2018, 9:56 AM

if is there any one who can help me to use IntentServices in dagger2 ?

stackoverflow 2

deviant

11/07/2018, 10:54 AM

what is more efficient way to check if property instantiated?

::logger.isInitialized

logger==null

i mean should i avoid

isInitialized

lateinit feature due to reflection magic?

mikehearn

11/07/2018, 12:18 PM

just wondering if there's an overload somewhere for it

CamilleBC

11/07/2018, 12:55 PM

Hey guys ! Is there an equivalent way in Kotlin to download a file from a URL without buffering into mermory? Like with Java.NIO?

CamilleBC

11/07/2018, 1:05 PM

Thanks! I'll first try using the java.nio classes. I don't why I didn't just try that 😄

karelpeeters

11/07/2018, 2:51 PM

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val str = "hey"

when (val line = str) {
    "abc" -> println("abc")
    line.startsWith("h") -> println("starts with h")
}

Any reason this doesn't work? It says

Incompatible type: Boolean and String

on the

.startsWith

part.

karelpeeters

11/07/2018, 5:11 PM

Is there currently a way to define sealed class inheritors in multiple files? They're getting a bit too big for a single file.

beepdog

11/07/2018, 7:15 PM

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object RTMMessages {
    sealed class Message(val id: Long, val type: String, val channel: String){
        class Typing() : Message(id, "typing", channel)
    }
}