I'm a newbie. I need help with Chuck Norris cipher package chucknorris fun main() { println("Hello World!") } I don't know what to do🙏

Is there any way to make the

ordinal

field of an enum start by 2 instead of 0? I'm using a third party ksp parser that uses the ordinal for something that I need to skip the first three numbers for...

Short from doing:

enum class Foo { NA1, NA2, NA3, Bar, Baz }

where NAx shouldn't be used... 😛

Is there any easy syntax/shortcut to declare a literal Java

Class<T?>

? E.G. I need a class literal for a

Double?

, so I was going to use

Double::class.javaObjectType

, but I have to “unsafely” cast that to make the compiler happy. Simplified example of what I’m doing, sort of: https://pl.kotl.in/OQI60v_tV

data class Coordinate(val x: Int, val y: Int) {
  val bottom: Coordinate = copy(y = y + 1)
}

I am trying to do the following thing, but I get

StackOverflowError

is it because I am trying to refer something that I am defining?

👋 Hello, team!

Hello, I want to deploy my Ktor App to Heroku. The deployment says “Build successful” but when I start the app, I get application error. Now I saw that I don’t have a .build/install directory in my build folder. This direcotry is referenced in the .Procfile as direction for heroku where to start the app. So how can I create this install directory? Thanks a lot!

Using the following code snippet, and some other code to profile it over 1M iterations with random numbers:

fun Pair<Int, Int>.sumIsEven() = (first xor second) and 1 == 0
fun Pair<Int, Int>.sumIsEvenAlt() = (first + second) % 2 == 0

I would assume the former to be faster as it doesn't require summing and dividing and just does bitwise comparisons, but I'm getting the following results:

=== Case 1 ===
Average: 42ns
Max: 546_802ns
Total: 42_349_933ns

=== Case 2 ===
Average: 36ns
Max: 52_984ns
Total: 36_907_022ns

What's the reason for this difference?

Hi, could someone tell me how to use one companion object field in another one ? why I get some error like

Variable 'xxx' must be initialized

? look the code below:

class CompanyResource {
    companion object {
        val allNames: Map<String, String> =
            mapOf(
                someone.first to someone.second // error: Variable 'someone' must be initialized
            )

        val someone =
            Pair<String, String>(
                "peter" , "blunt"
            )
    }
}

What's the best way to memoize the result of a delegated property when using

val x by delegate

? I could stick it in a cache in the Delegate class, but wondering if there's a simpler way... I suppose I could wrap it in a lazy, but I'd rather it was eagerly evaluated. I'm really only using it for syntax sugar to reduce boilerplate.

Is there any library in Kotlin or Java land that handles a data structure of ranges / intervals? I’ve been playing with https://github.com/lodborg/interval-tree for a bit, but it’s not quite what I’m looking for:

val tree = IntervalTree<Int>()

    tree.add(IntegerInterval(1, 4, Interval.Bounded.CLOSED))
    tree.add(IntegerInterval(6, 8, Interval.Bounded.CLOSED))
    // This ends up with three intervals [0,7], [1,4], [6,8]
    tree.add(IntegerInterval(0, 7, Interval.Bounded.CLOSED))

What I’m looking for is for the data structure to end up holding the “unified” interval of [0,8] after this third operation. And the same for deletion. If I have a single [0,8] interval and I remove [2,4], it should now have two intervals - [0,2] and [4,8].

Hi. Is there a library for parsing command-line options?

Does anyone have a sequence-based implementation for powersets (similar to what Guava provides)?

hey all, does anyone know where I can find the source code for common kotlin compiler plugins like noarg? have searched to no avail

why is this recommended? seems less intuitive to me

Why does

arrayListOf

and `listOf`exist? Both seem to be of Type ArrayList?

Can you get an annotation of a

KProperty

In Kotlin/JS?

I've just started reading the LinCheck guide. In the example given don't understand how the checker knows what

inc()

and

get()

are supposed to return, so how can it check if the values are correct?

why didn’t add

@JvmStatic

when converting java file to kotlin? this result occurs compile error

I don't understand why this function does not work. I expect to get two distinct results and instead I am getting all of the duplicates as well. Any ideas what I am doing wrong?

items(state.newsFeedItems) {println(listOf(it.feedTitle).distinct())}

why is this not compiling (complains about lateinit)?

class SpySleeper: Sleeper {
    lateinit var sleepDuration: Duration

    override fun sleep(d: Duration) {
        sleepDuration = d
    }
}

interface Sleeper  {
    fun sleep(duration: Duration)
}

why sources of some kotlin files are missing from the

kotlin-stdlib

sources jar?

Is there a

BiMap

(bidirectional hashmap)?

Given the lack of an android specific slack workspace, is there a channel here where a "NOT KOTLIN" but Android question can be asked?

How would I achieve the following?

open class A {
    open fun C.extMethod() { ... }
}

class B : A() {
    override fun C.extMethod() {
        // Somehow call A's implementation
        // Then do extra behavior
    }
}

super.extMethod(this)

doesn't seem to resolve unfortunately

Hello! Consider:

interface IFace {
  fun test()
  fun test2()
  // etc...
}

class A : IFace {
  override test() {}
  override test2() {}
  // etc...
}

class B : IFace {
  private val a = A() // Is it possible to specify that B must delegate all IFace functions to a without passing a in constructor? 
}

I am getting a weird error and I am not sure what is causing it or what I need to do to fix it. Consider the following: It appears to be something to do with Kotlinx Sterilization, but I'm not sure what part of my code is causing this.

java.lang.IllegalStateException: Symbol with IrPropertySymbolImpl is unbound
	at org.jetbrains.kotlin.ir.symbols.impl.IrBindableSymbolBase.getOwner(IrPrivateSymbolBase.kt:59)
	at org.jetbrains.kotlinx.serialization.compiler.backend.ir.IrBuilderExtension$DefaultImpls.searchForProperty(GeneratorHelpers.kt:342)

I can send a link to my code on Github if needed.

If I have a list of

data class Foo(val bar: String, val baz: Int)

and I want to only have a list with a unique

bar

with the max

baz

. Say [0] -> bar = "one", baz = 1 and [1] -> bar = "one", baz = 2, the resulting list should be in the same order and only contain [2]... how do I do this in the most concise and efficient way?

A quick question regarding

data class

and

set.contains(e)

If I didn't understand it wrong,

set.contains(e)

checks

elementInSet.equals(e)

. Also, data class creates

equals()

method for the properties in the primary constructor. Now, I'm wondering why I get this output:

data class Foo(var v: Int)

fun test() {
    val mySet = mutableSetOf(Foo(1))
    mySet.forEach {
        it.v += 1
    }
    println("mySet contains: $mySet")
    val f = Foo(2)
    println("$f in Set? ${f in mySet}")
    println("equals? ${f == mySet.toList().first()}")
}

Output:

mySet contains: [Foo(v=2)]
Foo(v=2) in Set? false
equals? true

Why

f in mySet

returns false?

Hi everyone, for all those getting started with Kotlin, I will be posting some videos under the topic “Kotlin Basics” and then move to more advanced stuff. Playlist can be found here, but I will be updating it every time I post something new.