kotlinlang #stdlib

to clear a possible validation error, so in my case there will be a lot more cases when validation error does not exist rather than when it does (user started typing, paused, continued). but I agree that it may not be common.

ilya.gorbunov

05/24/2017, 6:40 PM

This optimization is possible only when the map is immutable

dimsuz

05/24/2017, 10:48 PM

immutable as in "truly immutable" (that kotlinx library)? Otherwise we are already talking about a

Map

interface which is a read-only one and behaves as though it's immutable on a consumer side.

mg6maciej

05/24/2017, 10:51 PM

What Ilya meant is that you can call

someMutableMap - something

, which has to return new instance, because you could later modify

someMutableMap

. And because there is no difference between

Map

and

MutableMap

at runtime, how would you know when it's safe to return same instance?

dimsuz

05/24/2017, 10:55 PM

I was talking specifically about an extension method

Map.minus()

. I guess I didn't realize that there's no

MutableMap.minus()

. Which can be introduced separately... but now I understood that I could get some

HashMap

returned from java code and which one will be chosen then?... Right, so this can't be done I guess...

mg6maciej

05/24/2017, 10:56 PM

Nothing can stop you from doing this optimization in your code. Add

Map::betterMinus

🙂

dimsuz

05/24/2017, 10:57 PM

Yep, already did 🙂

dimsuz

05/24/2017, 10:58 PM

it's sitting as a private method in a particular file, because it's kinda perhaps a single use case where I do need this optimization.

05/27/2017, 3:35 AM

I'm trying to reference StringsKt.isNullOrBlank from Java and getting an error that it has private access despite being declared public in the stdlib source

05/27/2017, 3:35 AM

is this a function of the StringsKt__StringsKt stuff that the stdlib is compiled into for the JVM? or maybe just an IntelliJ bug?

05/27/2017, 3:58 PM

That's a shame.

miha-x64

05/28/2017, 7:41 PM

Copy code

infix fun Int.has(flag: Int) = this and flag == flag
infix fun Int.flagIf(condition: Boolean) = if (condition) this else 0

Haven't I reinvented a bicycle (or a wheel)? Or there's something similar in stdlib? 5 replies ++ for

inline

, I want

@InlineOnly

to be public for such tiny utils.

mg6maciej

05/29/2017, 11:30 AM

Copy code

inline fun <K, V, R> Map<K, V>.map(transform: (K, V) -> R): List<R> {
    return map { (k, v) -> transform(k, v) }
}

mg6maciej

05/29/2017, 11:33 AM

wonders if this could be added to #stdlib

mg6maciej

05/29/2017, 11:35 AM

Usecase is being able to write:

Copy code

myMap.map(::transformFunction)

instead of

Copy code

myMap.map { (myKey, myValue) -> transformFunction(myKey, myValue) }

👍 3

stepango

05/31/2017, 3:43 AM

@mg6maciej you could use smth like

Copy code

fun <P1, P2, R> Function2<P1, P2, R>.acceptPair(): (Pair<P1, P2>) -> R = { this(it.first, it.second) }
myMap.map(::transformFunction.acceptPair())

mg6maciej

05/31/2017, 4:33 AM

Or rather

acceptMapEntry

, but this is not the point. In my code I'm using the function I've put above (except made it internal) and it's much better than mapping

transformFunction

to another function that accepts different parameters, cause I just need

myMap.map(::transformFunction)

like normally when mapping `List`s. I'm just wondering if this is a good candidate for #stdlib, cause to me it feels like it is. There was an issue about it a while ago: https://youtrack.jetbrains.com/issue/KT-4167

mg6maciej

06/02/2017, 2:50 PM

Is there a way to learn what code using functions from stdlib can be injected by Kotlin compiler? Like

Intrinsics.checkNotNull

. I was thinking about making a really small lib by grabbing necessary stuff from stdlib into a jar, so that when having a lib in Kotlin, it would require only this lib when used from Java.

damian

06/02/2017, 2:57 PM

I think it used to be whatever was in the

kotlin-runtime

artifact. But I guess now it's assumed that anything in

kotlin-stdlib

is fair game

06/02/2017, 3:37 PM

Isn't that just ProGuard+JarJar?

06/02/2017, 3:37 PM

Then you get the absolute minimal subset instead of whatever goes into this hypothetical library

06/02/2017, 3:38 PM

Also, do people from Java actually care? We pull in libs with Guava deps and Scala deps and Rx deps etc. on the backend and as long as it doesn't impose those onto the consuming code no one cares

➕ 2

06/02/2017, 3:49 PM

And if it's for Android then you actually want the stdlib dep so that it can be shared and then collectively ProGuarded at the end

👌 3

voddan

06/03/2017, 3:11 PM

I couldn't find a way to concatenate iterables or sequences without coroutines ether. Could it be we are missing such a function?

ilya.gorbunov

06/03/2017, 3:12 PM

Hmm, what about

👍 2

voddan

06/03/2017, 3:16 PM

Oh, I missed

Sequence.plus(Sequence)

voddan

06/03/2017, 3:22 PM

but wouldn't such function make sense for iterables?

Iterable<T>(vararg subiterables: Iterable<T>): Iterable<T>

06/03/2017, 4:45 PM

We have that internally

ilya.gorbunov

06/05/2017, 12:59 PM

@voddan

sequenceOf(iterable1, iterable2, iterable3, ...).flatten()

is close enough

👍 2

voddan

06/05/2017, 4:34 PM

hm, nice! Should it be added to the idioms page?