is there a way to convert a KFunction to a lambda other than just casting it?

I'm looking at the code that I wrote before. There is cache:

val cache = MutableMap<String, Any?>

where value could be String, Int, Map, Array, etc. Then i retrieve values from it through the chain of functions, where caller is responsible to specify correct type.

cache[key] as R?

Question: what problems I may get with that approach? All of this code is internal to the module, and run on jvm/ios.

im really unsure why this is happening

If I have

val myvalue: MyObj by lazy {...}

, how I could inject different object to myvalue during testing?

What is the fastest way to check that 2 collections (lists with possible duplicates) have same content? 1. two containsAll calls 2. intersect and check size to each set 3. union and check size to each set 4. union size same as intersect size 5. anything else?

Hey! Say I have an arbitrary

List<Int>

where every entry is a counter. What would be a Kotlin-esque way to map this into a

List<Int>

where at every index the entry is equal to the sum of counts until that index? For example,

[1, 3, 4, 2, 2]

becomes

[1, 4, 8, 10, 12]

due to the following summations:

[1, 1+3, 1+3+4, 1+3+4+2, 1+3+4+2+2]

When would one prefer way 1 over way 2 or vice-versa for writing function

doSomething

?

//Way 1 (doSomething is a member function)
data class A(val item: String) {
        fun doSomething(): String{
            return item.toUpperCase()
        }
}

//Way 2 (making doSomething an extension function)
data class A(val item: String)
fun A.doSomething(): String {
        return item.toUpperCase()
 }

How I create a class with two "constructors" that on does not receive any value so run a big code block to init the properties and another that receives the properties already initialized?

Hi! 👋 I am trying to "flatten" a

List<Map<String, List<T>>>

to

Map<String, List<T>>

. If the original list of maps contain two maps containing the same String key, the lists should be merged / concatenated. I finding it hard to achieve this, could anyone nudge me in the right direction?

if (someArray[x] != null) { someArray[x].add(foo) }

Why does the compiler not recognize that

someArray[x]

cannot be null, and insists on

!!

?

Hey everyone, which server framework will you recommend based on your experience? Looking for minimal run-time dependencies, or even run without a server container like Jetty.

I want to extend a data class.

data class Hoge(val foo: String, val bar: String)

data class Fuga(foo: String, bar: String, val buz: String) : Hoge(foo, bar) // compile error

Data class in Kotlin cannot be opened, and its primary constructor must have only property parameters. I have two questions. 1. Why cannot data classes be opened? 2. How can I reuse

Hoge

class to define

Fuga

class?

Hi everyone, I am working with a local jfrog artifactory and I made build.gradle.kts file and followed how to configure it to integrate with the local repo, now I heared that the shadow plugin is good for making fat jars also in kotlin so I decided to use it, I wrote the following line inside my dependencies block: compile("shadow😒hadow:1.2.3") and it did pulled it from the local repo (can see the jar inside "external libraries" in intellij) but when I am trying to include the shadow plugin the build failed because it cannot find the shadow plugin which is very strange. Anyone have any idea how to add the shadow plugin properly?

Hello, I am modeling the reading of a

.csv

-file, and want to be as explicit as possible. The file comes in a strict format, and I am able to say for sure what content-type each column will have. For this reason, I want to model it explicitly, like so:

sealed class CsvField {
    data class ExternalId(val value: String) {
        companion object {
            const val index: Int = 0
        }
    }
}

So obviously there will be many more columns, which means the sealed class ends up looking extremely verbose when every data class has its own companion object, and there are like 15 of them. So back to my question; when my intent is to have 1 subclass of a sealed class with 1 constant, unchangeable field and one specified in constructor, is this the best way? Or am I missing something obvious? Is there a better pattern here? I tried with

enum class

first, but that way I don’t get to specify the value of the field, only the expected data. I could have a data class with the enum as type, and a plain string as value, but idk. Thoughts?

How can I do a loop like this but in Kotlin way, maybe using repeat or some another feature?

var isStopped =false

        do {

        }while (isStopped.not())

Hi everyone. I am java developer. Tell me please. How can i start learn kotlin? What the training exsercise or examples? I want starting learn Kotlin for back end development. I want to learn English the same way)

String.kt for example will use String.java on the JVM?

Hi anyone knows how to publish kotlin shared library in which can be used by iOS and Android? Thanks!

hi Is there any useful or popular web framework for kotlin. Something likes cakePHP or …..

Hi 2 all! please explain to me, what's difference? advantage?

Hi, could you help me spot the bug? The code here works, but the test fails with a message about invalid json. When i test it with postman and intellij idea's http file everything works. The error message:

Cannot transform this request's content to org.user5145.account.domain.aggregate.Account

https://pastebin.com/LZmcMx1u PS. it uses ktor

however, you can access Firebase via the REST API (https://firebase.google.com/docs/firestore/use-rest-api), and make the access by a Http Client like ktor

i'm sure there is a pretty way to express sth. like this in kotlin?

return if (sortedItems.isEmpty()) null else itemMapper.mapDto(sortedItems.first())

Hi all i am looking for a open source project to contribute please let me know if anyone have one

Hi, A few years a go i developed a game(currently still active with 1M+ downloads) on Android in java. After that project we moved on the Unity.. I want to get back into native Android but a lot has changed. Where do you guys recommend to start with? Im creating a simple test app to learn Kotlin and all the new patterns. But is MVP still a thing or should i go with MVVP and live data?

Anyone have any idea why I can't run a simple main function inside a class? Only if it's a standalone function I can run it but I can't run it if it's inside a class (even if it's given the jvmStatic annotation)

Anyone know how to solve this? Cannot access 'Serializable': it is internal in 'kotlin.io'

Hello guys, what's a fast way to get started with Kotlin backend development?

Anyone know how to fix this? This declaration is experimental and its usage must be marked with '@io.ktor.util.InternalAPI' or '@UseExperimental(io.ktor.util.InternalAPI::class)'