The most important questions have nothing to do with what tech you utilize. It’s how you architect your application. Your choice of template language, IDE, DB, etc, has no impact on that. Kotlin-React would not use templates. Generally with React style frameworks, everything is in one language (JS, Kotlin, Typescript, whatever). Separation of Concerns and adherence to other SOLID principles, etc. are totally in your hands. It sounds like you want: • An Android App • An iOS App • A Server Application • A Web Application Is that correct? I don’t see why this couldn’t be completely implemented in Kotlin if you really wanted to, there just might be some hiccups with Kotlin Native (but it is getting better all the time). KTOR for server, Kotlin multiplatform for mobile. There’s more to it than that, but honestly I’d start with one single aspect of what you’re trying to accomplish and build that out FIRST and then move on from there. Don’t try to learn every little piece of tech at once. Take your time.

Make things easy on yourself: Write the Android app in Kotlin using Android Studio, and the iOS app in Swift using Xcode. Using the default environments, especially for your first app, removes a lot of those decisions for you

Folks, dumb question: Is there any way to use the delegation mechanism on a property that is not declared in the constructor? something like this:

class X : List<Y> by myList { private val myList = mutableListOf<Y>()

Failing that as a simple declaration, is the clever way to do it maybe make the primary constructor private and offer secondary constructors to call it?

I think I started a new thread... fairly new to slack too, lol, oh man I must be getting old... I miss the days of assembly, lol, jk

Hello, I have a math equation

val result = value * 100.0 / 255

Given that 100.0/255=0.392, is

val result = value * 0.392

better than the equation one in the performance of view.

Is there a good channel (maybe even different slack instance) to ask questions about using PSI/UAST on koltin code? For example right now I'm struggling to figure out tell if a KotlinUParameter type is an inline type

My test so far uses no libraries except stdlib-jdk8 and RxKotlin

Let's say, there 2 functions with same signature but one is with a default parameter and the other is not. When invoking one of the function, how does the compiler figure out which one to pick? because when invoking the function, we have then 2 choice, either call one without the default parameter or one with the default parameter. But even if we invoke the function with the default parameter, somehow the compiler still invokes the function without the default parameter. I checked the bytecode but I could get much answer from it. https://pastebin.com/nqfsFLHH

Why is ktor's HttpClient(OkHttp) marked red in Intellij?

is there a kotlin conccurent set? kinda only find java ones

If I pass a method reference from Java to a Kotlin function, what do I put for parameter type? E.g.

MyJavaClass {
  MyKotlinClass myKotlinClass;

  void myMethod() { ... }

  ... myKotlinClass.foo(this::myMethod);
}

What should be the parameter in

fun foo( ? )

?

I'm trying to write a seemingly simple function, but Kotlin doesn't play dice, what am I doing wrong? declaration:

fun <E> Collection<E>.myContains(item: E) : Boolean

usage:

val isItInside: Boolean = listOf(1, 2).myContains("1")

expectation: usage fails to compile, because it's a

List<Int>

vs. a

String

https://stackoverflow.com/q/57224118/253468

I am trying to figure out how generate a null using simpleName. See this SO post: https://stackoverflow.com/questions/57229715/how-to-generate-a-null-using-kotlin-kclass-property-simplename

Please add a reaction to vote: 1️⃣ Immutable comparator performs better 2️⃣ Classic mutable comparator performs better 0️⃣ No real difference

Can extension functions, which are offered by Kotlin, be seen as a replacement for Utility classes and by that utility methods? At least most of the time not always

https://github.com/eugenp/tutorials/blob/master/spring-mvc-kotlin/src/main/kotlin/com/baeldung/kotlin/mvc/ApplicationWebConfig.kt I'm having an issue following that. Not sure where to put it and some of this stuff is depreciated. I've got a REST API in main.kotlin.org.app.web.api.apiController and I'm trying to make main.kotlin.org.app.web.js.jsController; basically my @RestController is working perfectly but I can't seemt o get my HTML/js @Controller to work. I was thinking the view resolver needed to be configured or something? New to kotlin, spring boot and smart IDE development.

I found myself doing bellow code very often when having a nullable variable in a class. Is there a less verbose pattern?

class SomeClass {
 
    var aVar: OtherClass? = null

    fun aFunction() {

        aVar?.let {
            //doSomething with aVar since 'it' is not null
        } ?: run {
            //doSomething else when aVar is null
        }

    }

}

I know that I can do this:

fun aFunction() {

    val aVarLocalCopy = aVar

    if (aVarLocalCopy != null) {
            //doSomething with aVarLocalCopy
    } else {
            //doSomething else when aVarLocalCopy is null
    }

}

But I don’t like the fact of creating one line of code to extract the thread safe local reference copy of aVarProperty. Any pattern or extension function to write above code shorter.

how to enable new type inference for the compiler?

How can I make an extension function to wrap this Java

mappingFunction

...:

@Nullable  V get(@NonNull K key, @NonNull Function<? super K, ? extends V> mappingFunction);

I really don't know what could be wrong:

suspend inline fun <reified K : Any, reified V : Any> Cache<K, V>.get(key: K, crossinline mappingFunction: suspend (K) -> V): V? =
	get(key) { runBlocking { mappingFunction(it) } }

it's probably related to the generics... 🤕

Let's say I want a collection, a deferred or whatever, of 2 types. Do you recommend:

//1
Something<Pair<A, B>>

//2
data class Other<A, B>(...)
Something<Other<A, B>>

//3
typealias Other<A, B> = Pair<A, B>
Something<Other<A, B>>

I'm expecting that the answer is "it depends", what are some good examples to choose which one to use?

So this code wouldn't even do the thing I had planned, but still. Why is it asking for a return statement? Any code below this line should be marked as unreachable. The right part of the assignment returns

Nothing

. This doesn't happen if assigned to a new var/val

I can not edit or run stuff on https://play.kotlinlang.org. Is it just me or does somebody else have the same issue?

which frameworks are you guys using when writing tests with junit5 which depend on docker? testcontainers? is there something out there which is a bit more kotlin'ish?

There is a spotify docker library?

Hey, so I want use ProGuard for obfuscation but each time when I want use reflection I have in bytecode `LKotlin/Metadata'. And there are too much about objects that I want hide. Is there any way to get rid of it? Or I need use java reflection?

Any built-in way to create a

Flow

of lines from a

File

(on JVM)? I thought about several options, like: -

FileReader(file).buffered().lineSequence().asFlow()

(requires to close reader externally) -

flow { FileReader(file).useLines { lines -> lines.forEach { emit(it) } } }

(broken reader closure it early termination) But I believe that would be using the blocking file API behind the scenes. Is this OK, though? Should I implement my flow on top of

AsynchronousFileChannel

instead?

How can I construct supertypes of a class/object in Kotlin?

[solved, see thread] I just found a funny edge case in the "when expression must be exhaustive" check:

fun foo(a: Boolean, b: Boolean) = when { // "when expression must be exhaustive" error
    a == b -> "same"
    a -> "first"
    b -> "second"
    // this actually IS exhaustive:
    //  a | b | result
    // ---+---+--------
    //  0 | 0 | same
    //  1 | 0 | first
    //  0 | 1 | second
    //  1 | 1 | same
}

Do you guys think this is an issue that should be reported? 🙂 edit: I am not sure because surely this is just one example of a whole bunch of those cases and I personally would not want to implement thousands of corner cases into a language feature. (After all, this is a language, not platformer physics 😄)

The documentation about Inline Functions declares that

inline

is used as

The inline modifier affects both the function itself and the lambdas passed to it: all of those will be inlined into the call site.

In case you want only some of the lambdas passed to an inline function to be inline, you can mark some of your function parameters with the noinline modifier:

What If I do not need to make the whole function inline but want that its passed lambdas are made inline? For example my function have private fields and to make it inline it is necessary to annotate the whole function with

@Suppress("NON_PUBLIC_CALL_FROM_PUBLIC_INLINE")

. If a function with lambda arguments is not marked as

inline

will the compiler smart enough to inline the lambda in the function body if the only lambda usage is its invocation? https://kotlinlang.org/docs/reference/inline-functions.html