i’d write that:

interface Database {
    fun getFoo(): String
}

class MutableDatabase(internal var foo: String) : Database {
    override fun getFoo() = foo
}

class ImmutableDatabase(internal val foo: String) : Database {
    override fun getFoo() = foo
}

why internal?

My proof of concept for this project is just styling HTML and converting it into a PDF but it's like shooting from the hip for page alignment, etc

I'm hoping I can avoid needing to create my own templating/styling engine dealing with raw PDFs, and just designate template items within the designer's workflow and fill it with kotlin, but I've been keeping my eye on PDF Box or iText if it comes down to it

Any recommendations for a good REST api framework? I’ve heard of ktor, but I’m wondering if there’s any other good options.

Vert.x is pretty amazing...more like a toolkit 🎉

anything special about annotations on properties in interfaces? I'm getting

This annotation is not applicable to target 'member property without backing field or delegate'

when I try to add

@DrawableRes

to an interface property

Is this class created from Kotlin source code?

I was thinking of Comparables, but that may not be so efficient, or binary searching, but I've also never used either in Kotlin and wouldn't know how's the best way to do this...

If I want to invoke a javascript function from kotlin, in a kotlin app running on the jvm, how do I do this?

Uhm this may sound dumb, but is it possible to use a

lateinit var

inside a

by lazy {...}

block of another

val

? I get the

UninitializedPropertyAccessException

when the class is being created.

are there breaking changes between 1.2.30 and 1.2.31? my intellijplugin seems to be 1.2.31 while the maven deps wants 1.2.30 (? I have no idea what is going on)

so then the element we’re adding is outside of the elements inside of the list we already have, right?

@ghedeon You can use

.apply

function if you want to insert something in the middle of fluent call chain:

someList
    .doSomething()
    .apply { if (condition) add(element) }
    .doSomethingElse()

anyone 🙂 https://discuss.kotlinlang.org/t/object-vs-object-declaration/7461 ?

Hi there, i'm trying to understand generics inside kotlin and i'm blocked. Given sample below i wanted to use in base class my FooList as param and extend this class where i'm using BarList. But i'm unable to

open class Foo {

}
class Bar:Foo(){

}
open class FooList {
	open var list:List<Foo>?=null
}
class BarList:FooList(){
	override var list:List<Bar>?=null
}
open class BaseTest {
 open var llist:List<FooList>?=null
}
class BaseTestTwo : BaseTest {
	override var llist:List<BarList>?=null
}

What is the cleanest way work with a chain of

Optionals

when you need to hang on to intermediate values? (“Promise Hell” in JavaScript) Sample:

return receiptRepository.findOne(receiptId)
    .map { lineRepository.findOne(it, lineId) }
    .map { lineRepository.update( /* need receipt here */, it, updatedLine) }
    .map { ResponseEntity(it, HttpStatus.OK ) }
    .orElse { ResponseEntity(HttpStatus.NOT_FOUND) }

In Kotlin, if I’m using

by

to delegate the implementation of a Java 8 interface containing default methods to something, does anybody know if methods with default implementations on the interface are supposed to be delegated or not?

Fortran

that’s a name I haven’t heard in a long while 🚬

Anyone have a recommendation for what I should do for logging? I looked at kotlin-logging but I couldn't figure out how to log to a file / do configuration, etc?

pretty good library

I want to learn kotlin from android, I don't know from where to start. I know kotlin official site is there, but except that please help me the website or YouTube videos which I can follow to learn kotlin

@Smit Aen https://developer.android.com/kotlin/get-started.html Can also recommend https://www.amazon.co.uk/Kotlin-Android-Developers-Learn-developing/dp/1530075610 & I think that the author @antonioleiva also runs an online course

Hey guys I’m stuck with a kotlin generics problem: How to inherit from same generic interface twice with two different types?

interface A<T> {}

class B: A<Apple> {}

class MyClass: B, A<Orange> {}

Kotlin gave me an error: Type parameter T of ‘A’ has inconsistent values: Apple, Orange

The compiler probably "knows" that

is Nothing

is always

false

.

Let us move to thread, as this seems to cause quite a lot of clutter in global channel.

yeah - I think that might be the reason

val date = LocalDate()

date.dayOfMonth = 4 // this does not compile because dayOfMonth only has a getter, and no setter

you could write an extension like

operator fun <K1, K2, V> Map<Pair<K1, K2>, V>.get(key1: K1, key2: K2) = get(key1 to key2)

, etc.

you can get pretty far just wrapping a

Map