kotlinlang #announcements

Could someone point me to the correct channel to inquire more about the Kotlin playground? I’d like to see if anyone has done integrations to render more than just console output.

pardom

01/10/2020, 7:08 PM

i.e. jsbin/jsfiddle but with kotlin.

James Hilliard

01/11/2020, 1:49 AM

anyone know what is causing this error(using kotlin 1.3.61)?

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Caused by: java.lang.AssertionError: Descriptor should be not null: ReactiveAuthenticationManagerResolver { request: ServerHttpRequest ->
            if (request
                            .path
                            .subPath(0)
                            .value()
                            .startsWith("/employee")) {
                return@label Mono.just(employeesAuthenticationManager())
            }
            Mono.just(customersAuthenticationManager())
        }
        at org.jetbrains.kotlin.codegen.ExpressionCodegen.getNonLocalReturnInfo(ExpressionCodegen.java:1674)

🙂 1

James Hilliard

01/11/2020, 1:49 AM

it's a

e: org.jetbrains.kotlin.codegen.CompilationException: Back-end (JVM) Internal error: Failed to generate expression: KtBlockExpression

error

Vlad

01/11/2020, 12:19 PM

Is there any way to write inner class in separate files but link parent class? Got an awkward framework where its not easy to pass parent ref, but using inner classes everything works perfectly except code gets huge with many lines in one file.

ursus

01/11/2020, 12:27 PM

hmm maybe just collapse the class body in intellij

ivano

01/11/2020, 9:12 PM

I studied that I can change inner anonymous classes with

object

to a lambda if and only if the object type is an interface

ivano

01/11/2020, 9:12 PM

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fun search(query: String) {
    view?.showLoading()

    repository.getRecipes(query, object : RepositoryCallback<List<Recipe>> {
      override fun onSuccess(recipes: List<Recipe>?) {
        <mailto:this@SearchResultsPresenter.recipes|this@SearchResultsPresenter.recipes> = recipes
        if (recipes != null && recipes.isNotEmpty()) {
          view?.showRecipes(recipes)
        } else {
          view?.showEmptyRecipes()
        }
      }

      override fun onError() {
        view?.showError()
      }
    })
  }

ivano

01/11/2020, 9:13 PM

in this case I have the method

getRecipes

that has two parameters, I would put outside the second parameter transforming it as lambda but does not work

Hullaballoonatic

01/12/2020, 12:49 AM

Is the following a trade-off? • run-time default values for function parameters and class fields • erased type-parameters That would make sense if so, because I noticed c# has no erased types, but also only allows compile-time default values for the former

❓ 1

pavlospt

01/12/2020, 8:48 AM

Hello friends, I have a question regarding the experimental APIs of Kotlin, like Contract methods for example. Is there anywhere, a roadmap about each such feature? Is it public information when Jetbrains plans to transition them to stable?

Manuel Lorenzo

01/12/2020, 5:21 PM

thanks!

Czar

01/13/2020, 1:08 PM

I'm drafting an API implementation, started with a model like this:

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abstract class UnsignedRequest {
  abstract fun signatureData(): String
  fun <T : UnsignedRequest> sign(signer: (String) -> Signature): SignedRequest<T> =
    SignedRequest(unsignedRequest = this as T, signature = signer(signatureData()))
}

data class SignedRequest<T : UnsignedRequest>(
  @JsonUnwrapped val unsignedRequest: T,
  val signature: Signature
}

Is there a way to make

sign

method type-safe? I really don't like the unchecked cast to the type parameter:

this as T

. So far I came up with this, which is at least type safe, but repetitive, as I'm essentially copying the signing logic:

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interface UnsignedRequest {
	fun signatureData(): String
	fun sign(signer: (String) -> Signature): SignedRequest<*>
}

data class SignedRequest<T : UnsignedRequest>(
  @JsonUnwrapped val unsignedRequest: T,
  val signature: Signature
}

data class ActualUnsignedRequest(/* properties */) {
  override fun signatureData(): String = /* some composition of properties */
  override fun sign(signer: (String) -> Signature) : SignedRequest<ActualUnsignedRequest> =
    SignedRequest(req = this, signature = signatureData().let(signer))
}

UPDATE: Silly me 😄 Forgot about extension functions' awesomeness!

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inline fun <T : UnsignedRequest> T.sign(signer: (String) -> String): SignedRequest<T> =
	SignedRequest(req = this, signature = signatureData().let(signer))

ESchouten

01/13/2020, 1:57 PM

Kotlin 1.3.70 EAP 1 released https://github.com/JetBrains/kotlin/releases/tag/v1.3.70-eap-42

K 10

dave08

01/14/2020, 2:55 PM

Is there a way to create a

ClockMark

from an existing time in milliseconds (a long value)?

user

01/14/2020, 4:21 PM

https://twitter.com/kotlin/status/1217119469727879168 Run the "Show Kotlin Bytecode" action and then click on "Decompile" to check how something is implemented under the hood and see the Java code that corresponds to the Kotlin code #KotlinTips https://t.co/JK8vRiORn3 Twitter

👍🏾 2

Tristan

01/15/2020, 4:12 AM

Microsoft is taking over (once again) with Blazor https://devblogs.microsoft.com/aspnet/mobile-blazor-bindings-experiment I cannot wait to see what will happen with Kotlin multi platform and Jetpack compose multi platform Should it be a community effort or JetBrains is working on something ?

Robert

01/15/2020, 12:05 PM

Can I load C++ libraries in Kotlin MP thru JNI (or something else)? Are there restrictions?

Robert

01/15/2020, 12:08 PM

Or can I somehow create a binding using common and native kotlin, and use that in common (jvm/js) code?

user

01/15/2020, 3:42 PM

https://twitter.com/kotlin/status/1217472055974813698 Curious about what font we’ve been using for #KotlinTips all this time? It’s the new font from JetBrains: JetBrains Mono! https://t.co/AHbo6W3nV4 https://t.co/8nkoXv7jLL Twitter

Sylvain Patenaude

01/15/2020, 5:09 PM

Anyone would know how to remove this warning:

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sourceSets {
    commonMain {
        dependencies {
            implementation kotlin("stdlib-common")
        }
    }

The warning is:

'kotlin' cannot be applied to '(java.lang.String)'

. Posted in #gradle

Darren Bell

01/16/2020, 9:15 AM

Hi. I was wonder what would be the idiomatic way to implement the "Pipe and Filter" architectural pattern in Kotlin

addamsson

01/16/2020, 9:46 AM

Come on JetBrains!

Daniel Medeiros

01/16/2020, 6:52 PM

I published an article on Kotlin Coroutines https://medium.com/@mobitv/a-simplified-guide-to-kotlin-coroutines-edc9149ad54f

👍 7

Matthieu Stombellini

01/19/2020, 4:44 PM

Seems like this was an OpenJ9 issue. Issue does not happen when using HotSpot

james

01/19/2020, 10:32 PM

I have a question about

sortedBy

and

sortWith

if anyone can help? I want to provide a Comparator which compares two things, first being

it is SomeType

and the second being

(it as? SomeOtherType)?.stringField

I can see how to do this with two chained

sort

functions, but I'd like to know how to do it with just one