Hey! I want to get array[0].. But I want to ensure that the array is at least size >= 1 In Kotlin, is there an easy way / shortcut to do this? [10:36 AM] Instead of doing if( array.size() > 0){ … } [10:36 AM] If not, you could probably make an extension function

Hey! Is there a built-in way of determining if an int falls within a number range?

I need to create a list of all the `m`’s produced by this cartesian product. Is there a nice idiomatic way to do this? Am I missing some kind of built in cartesian product function?

messages.forEach { message ->
            recipients.forEach { recipient ->
                val m = messagingService.recordMessage(message, listOf(recipient))
            }
        }

Does Kotlin method delegation really break whenever a default implementation is added for a method of the delegated-to Java interface? Suddenly the default implementation instead of the delegate's implementation is called. As far as I can tell, my Kotlin code broke simply by updating to a new JDK version that adds default implementations to existing interfaces.

message has been deleted

Is there a way to get a

KType

from an

Any

(or the corresponding KClass<*>) or am I stuck with only having access to the

KClass<*>

?

Hello. I am using 1.4-M1 with worksheets script (.ws.kts). Is it the right channel to talk about worksheets Intellij feature?

anyone who would know, why following code fails because of type inference ?

Is there a more succinct way of doing this in Kotlin?

Does kotlin have any way to generate random unique id in compile time. I mean id is random, but is const for runtime? So i can write compiler plugin, but may be community already has solution. For example: // sourse fun a(): String = CompileTimeId.nextId() // compiled code fun a(): String = "hdhdjdnwld"

I.e.

abstract class ReceiverClass {

 open fun String.onSomethingHappened(){
   println(this)
 }
}

class Child  : ReceiverClass(){

  override fun String.onSomethingHappened() {
    super.onSomethingHappened() <-- doesnt compile
    println("hello world")
  }
}

Is it a bad practice to have lambda inside lambda?

(String) -> (() -> Unit)

Or is there any side effects?

Anyone know if this is in the tracker yet or even fixed in newer releases? https://play.kotlinlang.org/#eyJ2ZXJzaW9uIjoiMS4zLjYxIiwiY29kZSI6InByaXZhdGUgaW5saW5lIGZ1biBmKGNyb3NzaW5saW5lIGNpOiAoKSAtPiBVbml0KSA9IG9iamVjdCA6IFIoKSB7XG4gICAgb3ZlcnJpZGUgZnVuIGcoKSB7XG4gICAgICAgIGNpKClcbiAgICB9XG59XG5cbnByaXZhdGUgdmFsIHByb3AgPSBmIHt9XG5cbm9wZW4gY2xhc3MgUiB7XG4gICAgb3BlbiBmdW4gZygpIHt9XG59XG5cbmZ1biBtYWluKCkge1xufSIsInBsYXRmb3JtIjoiamF2YSIsImFyZ3MiOiIiLCJqc0NvZGUiOiIifQ==

Which one would you go for: 1. Implementing your repository/manager directly

interface Manager { ... }

class ManagerImpl(...) : Manager {

    override fun functionality(): SomeShenanigans {
        return Shenanigans.create { ... }
    }

    ...
}

2. Dividing implementation into multiple small functions

interface/typealias Functionality: () -> SomeShenanigans

fun functionalyImpl(): SomeShenanigans = Shenanigans.create { ... }

class ManagerImpl(f: Functionality, ...) : Manager {

    override fun functionality(): SomeShenanigans {
        return f.invoke()
    }

    ...
}

The former is much more compact but can cause circular dependencies and would require some weird shenanigans to solve, while the later solves the issues with circular dependencies but would require much more boilerplate.

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For library authors
As creating new libraries is vital for the Kotlin ecosystem, we keep improving the experience of library authors. The new library authoring mode will help shape your code in the way that's best for stable APIs. Also, we are going to release Dokka 1.0 to support docs generation for all platforms.

From https://blog.jetbrains.com/kotlin/2019/12/what-to-expect-in-kotlin-1-4-and-beyond/ Can one read about this anywhere ?

Say I have a method called as

.method(true)

or

.method(false)

. I would like to migrate that to

.method(SortOrder.ASC)

and

.method(SortOrder.DESC)

respectively. Can I do that with

@Deprecated

or something similar that can be triggered on an entire project? (I can easily end up with

.method(if(true) SortOrder.ASC else SortOrder.DESC)

but I would like to automate the final step)

gRPC Kotlin launched today — check out the docs at grpc.io to try it out! Shout out to @Brent Shaffer and the rest of the team that worked on this

Hey guys, I’m looking for some recommendations/advice! I’m trying to automate code standards for my project…. First want to do simple things such as: • Check the top of the file to ensure it has a copyright + specific comment format • Enforce Kdoc/JavaDoc format for our functions I would like it to either Flag Bitbucket PR’s or reject builds if they do not comply I’ve already used File Templates & Live Templates… But this acts more of an aid instead of actually enforcing standards My current thinking is to use Android Lint and tie it to gradle to fail builds if they don’t comply, but I haven’t really researched this approach yet… • Starting to read up KTlint

hi, new to kotlin and playing with inline classes as a replacement for value classes

inline class TypesafeId<T>(val id: Int)

typealias PersonId = TypesafeId<Person>
data class Person(val id: PersonId)

typealias AnimalId = TypesafeId<Animal>
data class Animal(val id: AnimalId)

fun main(args: Array<String>) {
  println(Animal(AnimalId(1)))
  // println(Person(AnimalId(1))) typecheck fails at compile time 
  println(Person(TypesafeId(1)))
}

wondering why the last

println

compiles successfully?

are these 2 expressions equivalent in kotlin? assuming var start = 0

start += 1  // expr1
start++    // expr2

I have a fairly large kotlin backend app, 14 KLOC, 1.3.70, gradle-based. If I want to improve compile times for edit->compile->run in IntelliJ, where do I start (using IntelliJ:s built-in compiler, 2020.1)

My project seems to no longer finish compilation after bumping a dependency. Is there a compiler option or something that shows which file the compiler is currently compiling to narrow the problem down ?

I am trying to use the better-parse library to parse a file. The file has the following structure:

Header
LineItem
LineItem
Footer

I have written a

Grammar<T>

to parse each line of each "type" so far, e.g.

Grammar<Header>

. How can I compose these grammars together? The lines are split by newline.

this code

fun generate(){
    println("${randomWord()}${randomKey()}${randomWord()}${randomWord()}${randomKey()}${randomWord()}${randomSymbol()}${randomWord()}${randomSymbol()}")
}

prints

String Int String String Int String Char String and Char

respectively and how do i make this code to change it place randomly in every run that can be

String  String Int String Int Char String Char String

kinda a lazyweb question, but i couldn’t find a very good kotlin solution. what’s the best way to find the union of a set of intervals. for example: given: [1,3], [2,5], [8,9] result is: [1,5], [8,9]

Hello, is there any elegant way to define a sealed class of data classes with common vals?

Hey guys, using Gson, I made a generic method that performs a deep copy on an object.

inline fun<reified T> Any.deepCopy(): T {
    val JSON = Gson().toJson(this)
    return Gson().fromJson(JSON, T::class.java)
}

However, when I try to perform this Deep Copy on a List, the items on the list are

LinkedTreeMap

. Can anyone correct me as what can I possible do to resolve it?

I’m a student currently writing his bachelors thesis about a DLT Application in M&A. I’ve decided to build a simple but working prototype to facilitate the Q&A Process on the Corda Ledger. (which is simply exchanging text in a verified manner) Problem is: I have no prior coding experience (no java, no kotlin, but I’m doing Kotlin as it seems easier) and only very roughly understand the code and what it does. So basically an absolute noob. I need to have a working prototype ready by next week Friday as the dealine is approacing fast. I was hoping to find someone who can guide me on how to build it and help me find solutions. So if there is any volunteer out there who wants to help a struggling student, please contact me. I can really use the help. 🙂 I would need someone to check my kotlin code and explain a counple of things to me… Cheers, Ludwig