hi! i’m super new to kotlin/intellij/gradle. trying to make a k/n project that compiles to macOS and runs macOS tests. the problem I’m having is that

macosTest > kotlin > sample > SampleTestsMacos.kt

isn’t finding the

kotlin.test

modules. i tried to add the dependencies to the

macosTest

sourceSets section, but i’m still just missing something.

(or should I just go with Java's ones)

the return@asUncancelableObservable hurts my eyes

Hi! I have a list of objects, lets say a list of Person. I want to remove all duplicates from that list based on the combination of person.name and person.age. What is the "kotlin" way to do so?

would it be overflowing?

Is there an elegant way to split a list of Person for every 10 persons and return a list of object Group(persons(10 or less/rest))?

i'm trying to parse an environment variable with a sensible default, and since this is a learning experiment as much as anything else, i'd like to use pattern matching. is this is a sensible approach, or should i stick to assigning the value of a

try/catch

?

val port: Int = when (val p = System.getenv().getOrDefault("PORT","8080").toInt()) {
      is Int -> p
      else -> 8080
    }

Is it possible for a class to extend 2 lambdas somehow, given they are interfaces?

class ApiReactionMapper() : (ApiReaction?) -> Reaction?, _(Reaction?) -> ApiReaction?_ {

Is it possible to use visibility modifier to have a class which can be returned by a factory but that cannot be created otherwise? Thanks

Is that the best way to build a map for a type that only handles length and item(x) :

/**
 * Applies the given [transform] to each of the Nodes from the NodeList
 *
 */
inline fun <R> NodeList.map(transform: (Node) -> R): List<R> {
    val array = ArrayList<R>(this.length)
    for (n in 0 until this.length)
        array[n] = transform(this.item(n))
    return array
}

I am taking a Kotlin class at Coursera and in the interactive code challenges I see eq in

list1.allNonZero() eq true

, but when I copy code into IntelliJ I get unresolved reference. Is eq part of Kotlinlang or hidden extension in the course code?

regarding Sequences (which I totally overlooked, thanks @sitepodmatt): https://typealias.com/guides/kotlin-sequences-illustrated-guide/

Shouldn't

val nodeId: UUID = UUID.randomUUID()

inside a data class generate a new uuid each time I make a new instance of the class?

override fun decode(databaseValue: Long) = when (databaseValue) {
        1L -> DbMessageType.APPOINTMENT
        2L -> DbMessageType.FILE
        3L -> DbMessageType.LINK
        4L -> DbMessageType.WEB_MEETING
        5L -> DbMessageType.PIN
        else -> DbMessageType.TEXT
    }

    override fun encode(value: DbMessageType) = when (value) {
        DbMessageType.APPOINTMENT -> 1L
        DbMessageType.FILE -> 2L
        DbMessageType.LINK -> 3L
        DbMessageType.WEB_MEETING -> 4L
        DbMessageType.PIN -> 5L
        DbMessageType.TEXT -> 0L
    }

to get unified - safer, without allocating Pair instance (or any other)?

someFun<SomeImplementation>()

and remove the

clazz

pqrameter.

Why

object A {
    sealed class B
    
    class C : B()
    class D : B()
}

gives

cane be inherited only by nested classes

, but

sealed class B
    
class C : B()
class D : B()

works fine?

I have a class that sorts a generic set of objects by name, and had been using a Function Interface to pass in a Function for getting the generic object's name for sorting. I've been struggling to find the Kotlin equivalent to accomplish the same functionality.

Ray Wenderlich Android Apprentice book looks promising but it is insanely expensive even in PDF and I didn't find relevant opinions about it

Kotlin in Action

User.find {
            Users[fieldName] eq fieldName
        }.firstOrNull()

I am using Kotlin Expose DAO Model! And Iam trying to buld a generic query to query for the fieldName by pasing it in. How can I do this? I mean, how can I access the field from

Users

by a variable?

feelsbadman.jpg

Is there any way to do kotlin koans in IDEA, but from different PCs? I pushed my code to github, but for whatever reason, can't import it through "Learn" menu...

I've got the most recent IDEA (installed today)

Hi all - not sure if this is the most appropriate place for this kind of question, but here goes: I'm trying to get my toes damp with Kotlin by working on a command line utility to do image conversions (specifically TIFF to JP2K (JPEG2000)). My general question is: how the heck do you pick libraries for this? I don't have any indepth familiarity with the Java library ecosystem (I know that it's vast). How do you all make determinations about these sorts of things? Many thanks in advance - I appreciate your time and trouble!

is there a better way to achieve this? I have a list and I want to compose it into 4 different lists

with(screens) {
            filter { it.showProgress }.mapTo(hasProgressScreens) { it.viewId }
            filter { it.showSkip }.mapTo(hasSkipScreens) { it.viewId }
            filter { it.showToolbar }.mapTo(hasToolbar) { it.viewId }
            filter { it.showBack }.mapTo(hasBackButton) { it.viewId }
        }

Hello all I'm adding entries to a map and I'd like to merge the values where the key already exists. For example, if I have:

val myMap = mutableMapOf<String, List<String>>()

and try to add:

myMap["a"] = listOf("1")
        myMap["a"] = listOf("2")

I'd like to have:

"a"=["1","2"]

How can I achieve this? Can I achieve it using an immutable map?

Can I have overridden

val

fields in an enum? Something like this? Or do I have to refactor them into getters?

enum class Foo {
    abstract val bar: String
    FIRST { override val bar = "FIRST BAR" }
    SECOND { override val bar = "SECOND BAR" }
}

i’m trying to use this library to extract a tar file https://github.com/kamranzafar/jtar but i’m having trouble converting the example to kotlin since assignment doesn’t work in while conditions. how can i accomplish the same thing in kotlin, or does anyone have a suggestion for a kotlin-first library for this task?

Can anyone tell me why I can’t write something like this

fun fatal(m: String): Nothing {
    with(TermColors()) {
        println(red(m))
        System.exit(1)
    }
}