Was expecting:

sealed class Element<T>(val value: T)

object Test : Element(10) // expecting compiler somehow able to refer the implicit integer 10 value to resolve T

But actually need to explicitly declare the argument type to satisfy the compiler:

object Test : Element<Int>(10)

Any reason why? Thank you.

Say my app version is using Kotlin 1.6.21, and I include two other dependencies that are using Kotlin

1.7.0

and

1.4.32

. Is there any possibility that there could be some sort of conflict since the versions are different? What about a similar situation with something like Jetpack Compose or Koin?

Anyone ever needed to make a class with an

init

block entirely lazy? Example in the thread. (I suspect I'm going to get "smells of a poor design" and that may well be right but my imagination is failing me on how to fix it at the moment...)

sealed interface EmptyResult {
    object Success : EmptyResult
    class Failure(val error: Throwable) : EmptyResult
}

sealed class DeleteResult : EmptyResult
sealed class SetResult : EmptyResult

Why can’t I access SetResult.Success or DeleteResult.Success?

Hello. I am trying to make a simple game based on choices. Do I have to make a new empty activity every time I want a new screen to appear when you lcikc a choice or is there any simpler way? Thanks!

Looking for suggestions on Coroutines book for server side applications (Non-Android platform). Any book which you would recommend here. thanks..

What’s a good way to read YAML and/or CSV?

Is there some library I can use for storing data efficiently? I've tried out exposed and ktorm but they are sorta confusing to me. i just want something simple but fast

Modernstorage

As postfix has greater precedence than prefix, then why

var num = 0
println(--num + num++) // equals to -2 instead of 0

Any way to make an object such as a sound start on background without a button on Android studio? I can make it as a button to start but haven't found resources to make it start automatically as the activity starts . Would really appreciate the help. Using kotlin language that is

What’s the function that sorts a list of things into buckets, like partition(list: List<A>, key: (A -> B)): Map<B, List<A>> ?

Is it normal that one adds useless

else

branch even if not needed in Kotlin 1.7? See say https://github.com/streetcomplete/StreetComplete/commit/1972a7139bff92e894474d1d3d1969b83da2d375 For example

private fun wat(element: StackUnderflow) {
    when (element) {
        is Unicorn -> {}
        is Multicorn -> {}
        else -> {}
    }
}

requires useless

else

where

sealed class StackUnderflow
sealed class Unicorn(val surface: Surface) : StackUnderflow()
sealed class Multicorn : StackUnderflow()
sealed class Tricorn(val surface: Surface) : Multicorn()
sealed class Doublecorn(val surface: Surface) : Multicorn()

is imported from another file.

i just found out about lateinit, this is super cool so that we don’t have to construct something using null 😒miling_face_with_3_hearts:

Any idea how to retrieve the version defined in build.gradle.kts so that i can use it in my code ?

How to use

reified

in a function that, when using a generic function, shows a compiler error message? The compile error message:

Cannot use 'T' as reified type parameter. Use a class instead.

there is something i don’t understand. is everything non-nullable by default (unless i use “?”) or is there something specific to write to ensure that something can’t be nulled ?

I found this problem when I was using

if-else-if-else

I'm trying to replixate the kogito quarkus example where they use this injection method:

@Named("approvals")
    @Inject
    Process<? extends Model> approvalsProcess;

When i try the same thing in Kotlin, i'm only getting an

[error]: Build step io.quarkus.arc.deployment.ArcProcessor#validate threw an exception: javax.enterprise.inject.spi.DeploymentException: javax.enterprise.inject.AmbiguousResolutionException: Ambiguous dependencies for type org.kie.kogito.process.Process<? extends org.kie.kogito.Model> and qualifiers [@Default]

exception. The same constructor injection 'way' actually works:

@ApplicationScoped
class FooBar (
    @Named(value = "approvals")
    private val approvalsProcess: Process<out Model>
        ){

But now i need to do the injection in my Test class for a unit test and i can't use this as its not allowed. only propery assignment is allowed

Apparently doing this:

@field: Named(value = "approvals")

actually works. No clue what this should do

Hi experts I can read in this kt.academy article that

Fan-out
Multiple coroutines can receive from a single channel; however, to receive them properly we should use a for-loop (consumeEach is not safe to use from multiple coroutines)

I wonder if this statement regarding consumeEach is still accurate? In which sense it is not safe?

Hello, I have a questions regarding transformation of list:

val result = myList
            .filter { it.nullableProperty != null }
            .map { it.nullableProperty!!.fromAccount }

Why do I have to use the non-null asserted call in the map step?

is

try-catch

idiomatic in Kotlin?

But is it actually an instance of that class? You cannot cast arbitrary instances to arbitrary types. You can only cast instances that are actually already of that type at runtime, but for which this fact is not known at compile time.

Is there some library I can use to generate graphs as image files? I just need some way to convert a map of values into a pie chart then export as a png or something similar

Is there static analysis tool which work for both kotlin and java?

is there some way to do

filterNotNull().filter { //… }

with one function?

better yet, is there an equivalent of

filter_map()

from, say, Rust?

I have java code that uses the pattern of say Inquiry().status(sts).notes(blah). Which enables chaining. what can i do from a kotlin aspect to define a similar class as that? the fields are not required, so you may want to set only 2 of those 3