Kotlin Test and annotation have been migrated so now is not necessary to add

-common

to implement them?

Hey guys, does anyone know when StateFlow (and MutableStateFlow) will be released? As far as I know, it's still at the experimentation phase.

Can Kotlin do something like this just in valid:

inline fun <reified T> options(options: T.() -> Unit): T = object : T {}.apply(options)

?

what is the Kotlin technology stack looks like ? compare with Java :

Can I tall the kotlin plugin to not add the sdlib for a specific module? I have a module that contains my android lint checks and there no implementation dependencies are allowed but only compileOnly ones.

My IDE (Android Studio) automatically updated the kotlin compiler plugin version to 1.4. Now my compiler is giving imaginary errors, probably because my gradle is still on 1.3.72 ( I cant change to 1.4 because of kotlinx.serialization breaking changes, sigh). How do I downgrade my IDE's kotlin compiler plugion from 1.4 to 1.372?

How is the idiomatic way to modify the value of a list for the desired object? I mean instead of doing it manually like list[1].name = "name" is there any other idiomatic way to do so? I want to modify all of the values of a list with different "names".

Given how Slack can end up as a "black hole" for otherwise high quality information, does anybody make a periodic digest of any of the kotlin language slack?

Hopefully this is the right channel to ask my question, if not please redirect me. I heard opinions that Kotlin is way quicker to write than Java and you can pump our projects/code faster, is this true? If so, by how much (% wise)

Since upgrading to Kotlin 1.4.0, I can't seem to use String.toBoolean() anymore. I always get the deprecation warning:

toBoolean(): Boolean' is deprecated. Use Kotlin compiler 1.4 to avoid deprecation warning.

It seems like this is not a well-functioning deprecation warning. There's no easy way to select the String?.toBoolean() version instead. Even if I cast to String?, the 1.4 compiler won't let me call String?.toBoolean() explicitly. It seems like a compiler bug.

I have a challenge for you guys: I have to create a domain model for a PaymentMethod. From the API I receive 2 values for each payment method: • id • transaction cost Let's say I have 3 different types of payment methods: • PayPal (id=1) • CreditCard (id=2) • Cash (id=3) I want to have subclasses for each payment method. The ID that is received from the API should be mapped to an instance of the matching subclass. I want to have subclasses because each payment method has some static data connected to it, that is defined client-sided (e.g. name, etc). If API returns an unknown ID, it can be ignored. Ultimately I would like to have a function in companion object of PaymentMethod:

sealed class PaymentMethod {
  abstract val transactionCost: BigDecimal
  
  data class PayPal(...) : PaymentMethod
  data class CreditCard(...) : PaymentMethod
  data class Cash(...) : PaymentMethod

  companion object { 
    fun create(id: Long, transactionCost: BigDecimal) : PaymentMethod {
      // TODO
    }
  }
}

Also I want to have a single source of truth for defining which ID belongs to which subclass (only define it once). Would like to hear some tips on how to implement this. If you think there are better approaches (except for modifying API) than what I want, feel free to suggest.

Hi, I have some Iterable extension functions I wish to contribute to the standard lib (this one I guess). I see there are already over 4000 branches. If I make a PR, will it be seen? I guess I'm just a little perplexed as there's no contributor instructions on the github 🙂 Any comments appreciated

How to view definition of the expect function from standard-library? Example: ArrayT.sort(). I tried to find a way in the Intellij, but so far no luck :<

QQ: If I am a library author, can I update the library's kotlin version without requiring its consumers to update as well? Specifically 1.3.72 -> 1.4.0

is there a way to enumerate all subclasses of a given class and instantiate single instance of each? without going into too much metaprogramming etc...

so sealedSubclasses works... now just to instantiate them?

I'm experiencing a really smoother IDE experience with Kotlin 1.4 due to the performance improvements. Couldn't be happier. Thanks Kotlin team 🙂

Why is it that the following code has no errors:

fun calculateNumberOfLengthBytes(data: ByteArray): Int {
    val l: Int = data.size
    return when {
        l < 128 -> 1
        l < 16384 -> 2
        l < 2097152 -> 3
        l < 268435456 -> 4
        else -> 5
    }
}

but, the following complains about "Incompatible types: Boolean and Int" in the comparisons

val data = byteArrayOf(5, 6, 7)
when(val l: Int = data.size) {
    l < 128 -> 1
    l < 16384 -> 2
    l < 2097152 -> 3
    l < 268435456 -> 4
    else -> 5
}

is there a slack server similar to this one but for spring framework?

I'm trying to update to Kotlin 1.4 and I have a Sequence<Long> that I call

max

on. I get a deprecation warning, so I run the "Replace with maxOrNull" fix, and it replaces

.max()

with

maxOrNull()

. So I put the

.

in front, and I get an unresolved reference error. There is no fix to import it. So I manually write the import (

import kotlin.sequences.maxOrNull

), and I still get the unresolved reference error, and the import is gray (unused). If I open

_Sequences.kt

I see

public fun <T : Comparable<T>> Sequence<T>.maxOrNull(): T?

Is there some trick that I'm missing here, or should I report this on YouTrack?

Not strictly Kotlin related, but does anyone know why the following JMH benchmark code

@Fork(1)
@Warmup(iterations = 5, time = 2)
@Measurement(iterations = 5, time = 2)
@State(Scope.Benchmark)
@BenchmarkMode(Mode.AverageTime)
@OutputTimeUnit(TimeUnit.MICROSECONDS)
open class Sha1Benchmark {

}

produces the corresponding error?

> Task :okio:jvm:jmh:jmhRunBytecodeGenerator FAILED
Processing 15 classes from /home/kevin/code/okio/okio/jvm/jmh/build/classes/java/jmh with "reflection" generator
Processing 2 classes from /home/kevin/code/okio/okio/jvm/jmh/build/classes/kotlin/jmh with "reflection" generator
Writing out Java source to /home/kevin/code/okio/okio/jvm/jmh/build/jmh-generated-sources and resources to /home/kevin/code/okio/okio/jvm/jmh/build/jmh-generated-resources

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':okio:jvm:jmh:jmhRunBytecodeGenerator'.
> A failure occurred while executing me.champeau.gradle.JmhBytecodeGeneratorRunnable
   > Generation of JMH bytecode failed with 1 errors:
       - Benchmark classes should not be final.
        [com.squareup.okio.benchmarks.Sha1Benchmark]

[Solved] I'm testing

java.nio

in Kotlin and I have a question: Why don't work

member references

to function is this case? *I know that with

Files.isDirectory(it)

work i*t

val stream = Files.list(folder) 
val files  = stream.filter {  it != null && Files::isDirectory } // error in Files::isDirectory
                   .map    { it!! }

Error Msg:

Type mismatch.

Required: Boolean

Found: KFunction2<Path!, Array<(out) LinkOption!>!, Boolean>

PD: Sorry, if this topic doesn't have to be in this channel, but I didn't find JVM channel.

Can I somehow call a suspending function inside a

Sequence#map

lambda? Or if not, is there some other construct to achieve the result?

how to combine two immutable lists into new immutable list? or add element to a list to create anew list. Something like newImmutableList = immutableList + element?

Is there a shorthand way of having a

MutableList<>

property with a getter that returns it as a

List<>

?

im working with an async library that returns a CompletableFuture; how could i convert it into a coroutine? (like Mono.fromFuture() does)

can Kotlin somehow match nested classes with

when

expression? something like Haskell can do, like

(Foo (Bar (Baz x))) -> ... something(x)

?

Is there anyone with knowledge about a project/github repository which makes some real use of kotlinx.html (not just hello world)? Would love to look into that. Thanks!

Any one had a problem with CSSBuilder removing periods on class names?

".clearfix" { clear = Clear.both }

in browser becomes

clearfix { clear = both }

So confused. It works elsewhere, but this is like another layer of css in.