You will understand whats the problem if you read the snippet it has lamda expression which I am trying to pass a parameter in a function

I am having some issues with library https://github.com/uchuhimo/konf in test classes import works fine, while in main intellij says unresolved reference 😞

implementation "com.uchuhimo:konf:0.20.0"

Hi people! What's a good channel to join to talk about development of the gradle plugin?

What is the difference between Kotlin Native and Kotlin Multiplatform?

upgrading to 1.3.60 has broken my project (see #kotlin-native for more on that). so I uninstalled the kotlin plugin and tried installing 1.3.50 from disk. now IDEA can't open any of my projects.

How do I pass a value of a non-null type to a method that accepts that type but as a nullable parameter? The other way around makes sense to safe-check, but if I'm giving you a non-nullable type as a parameter and you can accept nullable types, there's gotta be a way it can be taken

Is there a way to create static extension function to existing class?

Why the std-lib doesn't have a map implementation written in Kotlin, and instead uses platform-specific ones with expect/actual? Is performance the reason?

Am I not using higher-ordered-functions properly or is Kotlin’s type inference limited? (This is a silly example where I’m trying to get a “flow” or “left compose” operator - I know this is most natural with dot chaining in Kotlin.)

What is the relative performance of a `lateinit var`'s

isInitialized

? Is it just checking some flag, or is it some expensive reflective operation, maybe it allocates objects?

Hey guys! What's your usual take on having more than one class in the same file? I want to extract a piece of code from a complex class to a less-complex class and call it another service. However, this class will only be used by the class I'm extracting, and I don't really want to pollute the package namespace with a class that's not useful anywhere else. Should I keep it inside the same file?

How can I perform an action on a SimpleBooleanProperty change only once? Something like:

isConnected.onChange {
    timer.scheduleAtFixedRate(timerTask, 0, period)
    // unsubscsibe
}

, where isConnected is a SimpleBooleanProperty

Constructor executes before

private var mGlucoseState = GlucoseState.NONE

line

How can I be sure that casting is safe? Would the following be a completely safe cast, and thus not require a conversion function?

class Foo(vararg values: Int) : List<Int> by values.toList() {
    fun bar() = "foobar"
}

(listOf(1, 2, 3) as Foo).bar()

Casting is cheaper than conversion, because it doesn't require instantiating a new object, right?

Does the compiler optimize the following code so that the return value is not computed with every

toString

given that it never changes, or should I create a backing field?

class Foo(val str: String) {
    override fun toString() = str.reversed()
        .repeat(1000)
        .trim()
        .otherStuff()
}

I hate how clumsy IDEA and Android Studio are. All I did was create a new project called "Ben Leggiero's Résumé" and first it hits me with confusion over the apostrophe, and then this:

com.android.tools.idea.gradle.project.sync.ng.NewGradleSyncNotSupportedException: New Gradle Sync is not supported due to containing Kotlin modules

Using java code i can use interface with a single method just by using the interface name, like this:

val x = SomeInterface { }

Thanks to SAM. However when i try the same thing on kotlin interface I'm forced to create an anonymous class:

val x = object : SomeInterface {
  fun someMethod() { }
}

If i instead create a type alias for it I can write it without the object ceremony but I've no way of specifying what it is:

typealias SomeInterface = (): Unit

// ...

val x = { }

Yes i know i can do

val x: SomeInterface = { }

But picture this situation:

val x: SomeInterface = when (foo) {
  "A" -> { { } }
  "B" -> { { } }
}

I need double

{

, which is horrible. I think it would be much better to be able to write;

val x = when (foo) {
  "A" -> SomeInterface { }
  "B" -> SomeInterface { }
}

Is there a way to do this or a way to improve the previous example?

Why does Kotlin 1.3.60 push a constant 0 to the operand stack and then store it away before printing?

fun hello() {
    println("hello")
}

Bytecode:

public static final void hello();
    Code:
       0: ldc           #7                  // String hello
       2: astore_0
       3: iconst_0
       4: istore_1
       5: getstatic     #13                 // Field java/lang/System.out:Ljava/io/PrintStream;
       8: aload_0
       9: invokevirtual #19                 // Method java/io/PrintStream.println:(Ljava/lang/Object;)V
      12: return

https://kotlinlang.org/ Probably a bug

General question about experimental features, if anyone knows please. https://kotlin.github.io/kotlinx.coroutines/kotlinx-coroutines-test/kotlinx.coroutines.test/-test-coroutine-dispatcher/index.html Shows this as experimental. (In 1.3.2, which i think is the latest). Is there anyway to know in what version / when / if it'll stop being experimental? (for example with the Android Gradle Plugin they have alpha's where you know once that alpha goes stable channel)

Does anyone know why map on arrays returns a list and not an array?

Hey guys, I am basically doing a post request with ktor httpClient and I get back a HttpResponse successfully. With that I can see the response status and headers but I cannot see the body. How can I find the body?

a.mapIndexed { index, value -> value to myList[index] }.toMap()

?

Can you get an instance of

Class

object for top-level declaration, e.g.:

val x = ???::class.java.getResourceAsStream(...)

?

does anyone know how to capture a junit assertionerror that happens in a different thread? 🤔

Anybody know how to get a context in a regular unit test? Not an integration test.

Hey folks. Trying to figure out why accessing the

keyvalue

val inside this object is a problem:

class Tables(val session: Session) {   
   val queries = object {
        val keyvalue = object {
            val insert = prepare("INSERT INTO keyvalue (id, value) values (?, ?)")
            val select = prepare("SELECT * from keyvalue WHERE id = ?")
        }
        val timeseries = object {
            val insert = prepare("INSERT INTO timeseries (id, c, data) values (?, ?, ?)")
            val selectPartition = prepare("SELECT * from timeseries WHERE id = ?")
            val selectPartitionReverse = prepare("SELECT * from timeseries WHERE id = ? order by c DESC")
        }
    }
}

I’m not able to do essentially this:

tables = Tables(session)
tables.queries.keyvalue

anyone know why?

For the Kotlin KEEP process https://github.com/Kotlin/KEEP/ - does anyone know why discussions are meant to be broken up into an ISSUE istead of directly in a PR? I also see some discussion in the PR. Also, is the idea that if an idea is agreed upon after discussion in the issue the issue is closed and the PR is merged?

Is there any data on which spaces is kotlin most used on? I.e. Android, rest services, web clients, etc