i guess if i want Java projects to be able to use it - i’d have to.

Is it possible to make something like

run

or

with

work with an enum class? basically a way to introduce a scope where we can reference the enumerators without qualification

Is it somehow possible to have smart casts with type parameters? I have a situation where I have

interface Base<T>

and

Concrete<T : Any> : Base<T>

. In a method which accepts

Base<T>

I now need to check

is Concrete<T>

, but that's impossible because in the method

T

is not constrained to

Any

(but it has to be, if I have a

Concrete<T>

... See thread for more code.

I am trying to use

File.walk

however I am not able to get it resolved. IntelliJ always shows me

java.nio.file.Files.walk

instead of the extension

public fun File.walk(direction: FileWalkDirection = FileWalkDirection.TOP_DOWN): FileTreeWalk =
    FileTreeWalk(this, direction)

Hi guys, I would like to ask you that how could we check if the list is null only, the list could be empty that's fine but shouldn't be null, could someone help me?

What have I done wrong:

private fun <Long> List<Long>.combinationSums(): Sequence<Long> {
    val list = this
    return sequence {
        for (i in 0 until list.count()) {
            for (j in i + 1 until list.count()) {
                val sum: Long = list[j] + list[i]
                yield(sum)
            }
        }
    }.distinct()
}

I am getting a compiler error for the `list[i] + list[j]:

Unresolved reference. None of the following candidates is applicable because of receiver type mismatch: 
public inline operator fun BigDecimal.plus(other: BigDecimal): BigDecimal defined in kotlin
public inline operator fun BigInteger.plus(other: BigInteger): BigInteger defined in kotlin
public operator fun <T> Array<TypeVariable(T)>.plus(element: TypeVariable(T)): Array<TypeVariable(T)> defined in kotlin.collections

is there a trick to make overriden fields not null? for example in my own RuntimeException subclasses i want message to be String and not String?. actually, in this example the compiler could infere that message is not nullable for all subclasses of ApplicationException, or am I missing something?

open class ApplicationException(message: String, cause: Throwable?) : RuntimeException(message, cause)

Let's say I have two functions:

ImageView.photo(url: String) = { .. }
photo(url: String) = { .. }

Is there a way to call the second one in the scope of an ImageView like below?

ImageView(context).apply {
    ...
    photo(url)
    ...
}

Any help ?

Is there a way to generate any() objects for method params, so I don't end up with code that has a long list of any() in my test? It's not a vararg method, but maybe there's a way to use repeat or unpacking syntax?

_whenever_(myMethod(

_any_(), _any_(),_any_(), _any_(), _any_(), _any_(), _any_(), _any_())

).thenReturn

Hi, what's the best way to generate Typescript definitions for some Kotlin data classes? (a bit like Dukat in reverse?)

Hello, World! Isn't there a version of

String.map

fun that returns a String (instead of the generic one returning a List<R>) somewhere?

Will there be a recording of tomorrow's kafka with kotlin webinar https://info.jetbrains.com/kotlin-webinar-december-10-2020.html ?

Hi, does anyone else has problems with IntelliJ since the update to BigSur? In my case: after using the IDE for about 20 minutes my MacBook Pro (2019, i9) is running the IDE at 101 % CPU usage and the lag in the UI makes coding tedious.

I just found https://youtrack.jetbrains.com/issue/KT-24925, to allow short-hand notation for enum/sealed class values when the compiler can infer the type (so

foo(.Baz)

instead of

foo(Foo.Bar.Baz)

. It hope it’s considered for implementation in the relatively near future, would help greatly with verbosity!

Is there a cleaner way to do this? I don’t need the reference to the

stateDelegate

aside from the constructing the backing field and the public read-only state

// util
inline operator fun <T> StateFlow<T>.getValue(thisObj: Any?, property: KProperty<*>): T = value
inline operator fun <T> MutableStateFlow<T>.setValue(thisObj: Any?, property: KProperty<*>, value: T) {
    this.value = value
}

// usage
private val stateDelegate: MutableStateFlow = MutableStateFlow(...)
private var _state: State = stateDelegate
val state: StateFlow<State> = stateDelegate

fun foo() {
    _state = State(...)
}

Is there a standard way to exchange json data (text) between Kotlin and a Python program ?

is there a concurrent list/queue that can atomically return its content and clear itself afterwards ?

Hello, can someone tell me what name it is showing for me? Sbeve or something else? I am new to slack

Hello all, please consider adding your thoughts into this issue: https://youtrack.jetbrains.com/issue/KT-43876

I have a lazy transient property in a

<http://java.io|java.io>.Serializable

class. However accessing

foo

from

@delegate:Transient val foo: Foo by lazy { }

causes a NPE on deserialization. How can I create a lazy property that the VM does not try to serialize, but at the same time does the right thing?

Is there a way to check if something is an object vs. a class? For example, how could I create this if statement?

sealed class Fruit {
    class Apple(val color: String) : Fruit()
    object Orange : Fruit()
}

fun main() {
    val list = listOf(Fruit.Apple("red"), Fruit.Orange)
    for (item in list) {
        if (/* item is object? */) /* do something */
        else /* do something else */
    }
}

Quick question: are annotation processing compiler-only or can they be at runtime as well? I can't seem to find an example of such.

Maybe this is something "basic" but I had some argue with a colleague.... about the run scope function, when I do:

val result = run { ... }

result is not actually calculated there, but when is needed (lazy), isn't it? I know this is the usual behaviour when using a functional style but I couldn't find any reference to give a clear explanation to my colleague.

How do single devs meaning devs that work because they have just started or something make icons? do they make them themselves?

Hello, I am creating a koltin lib t be used on the

jvm

. I am using a bunch of

Deffered<*>

for async calls, how do I extract and await the values of

Defered<*>

from Java code?

Hi folks, can someone please tell me why the following isn't possible?

object MoonWidgetInput
object MoonWidgetOutput
object MoonWidgetData

abstract class BaseVehicle<INPUT, OUTPUT>

abstract class BaseWidget<INPUT, DATA, OUTPUT>() {
    abstract var vehicle : BaseVehicle<INPUT, OUTPUT>
}

class MoonRover : BaseVehicle<MoonWidgetInput, MoonWidgetOutput>()

class MoonWidget : 
    BaseWidget<MoonWidgetInput, MoonWidgetData, MoonWidgetOutput>(){
    override var vehicle = MoonRover()
}

I want to build a "2D array", and set and change elements in it. I think a mutableList does not work well, because i cant not randomly set elements in it. It gives a index out of bound exception. Is there a autogrow option? or should i use a different data structure?

if I try

var cb = new Function1<? extends InputTextCallbackData, Boolean> (() -> true);

then the

extends

complains

Wildcard type '? extends imgui.classes.InputTextCallbackData' cannot be instantiated directly

Why is callbackFlow still marked experimental? As far as I know this is the official way of wrapping another api emitting multiple value (register / unregister). If I want to write a library using

callbackFlow

does that mean that it may become binary incompatible in the future? Thanks.