BTW, is there an issue tracker for Kotlin stdlib?

Is there any way to get the seed of

kotlin.random.Random

? I want to use

Random

in a test with random seed which I could print in case the test fails.

The same can be said for

%

.

Or

^

or

|

Has the introduction of something like:

fun <T> Boolean.map(valueTrue: T, valueFalse: T): T = if(this) valueTrue else valueFalse

in the stdlib been already asked/taken into consideration?

I think it could be great to add

countIndexed

and

sumByIndexed

to the stdlib. In an effort to remove a

var

and a

forEachIndexed

, I came across this need. However, I'd not want to bloat the stdlib. Please, add your ➕ if already needed one of these functions.

Idea: A

joinToString

parameter which allows something like that:

listOf(1,2,3,4).joinToString(separator = ", ", lastSeparator = " or ")

->

"1, 2, 3 or 4"

hey guys, silly question: what's the best way of formatting a Float/Double to String with a given number of decimals in Kotlin common? Is there any plan of integrating a

.format

or

.toString(decimals)

in the common stdlib?

There are some functions I use so often they may be useful for the stdlib 🙂

val <C : CharSequence> C.nonEmpty
	get() = ifEmpty { null }

val <CollectionType : Collection<*>> CollectionType.nonEmpty
	get() = ifEmpty { null }

val <Element> Array<Element>.nonEmpty
	get() = ifEmpty { null }

val actualNonEmptyString = inputString?.nonEmpty ?: error("is required")
val actualNonEmptyList = inputList?.nonEmpty ?: error("is required")

We have

hashMapOf()

by now but no

toHashMap()

🙂

Map<K, Set<T>>

or

Map<K, Iterable<T>>

will also be perfectly fine, I'm mainly concerned about the grouping aspect and not the explicit return type

What do you think about adding

Option

class? The use case https://youtrack.jetbrains.com/issue/KT-29026

If i have a list of pairs (to and from) and want to get the distinct sorted pairs that occur the most what would be the most functional way of doing it? So

[(1,2) , (3,4), (1,2)]

should return

[(1,2),(3,4)]

Hello, were can i see changes to stdlib from version to version? I mean like in kotlin release notes. What was added or improved in stdlib...

In the kotlin stdlib the

LinkedHashMap

does not have the

accessOrder

property that the

java.util.LinkedHashMap

has. Is there a replacement if I want to use such a functionality, for example for as a LRU cache? Or should I look for a third party library for simple LRU caching (with kotlin multiplatform support)?

Why is it

interface Comparator<T>

instead of

interface Comparator<in T>

? Like, I know theoretically you shouldn't have to specify that the

T

has

in

variance, but in common code errors will be shown if you do something like

interface Sort<in T>: Comparator<T>

, saying the

T

in

Comparator

is

invariant

.

is there a function analogical to

let

but for empty strings

someString?.let { calculate(it) }

I need

someString.doIfNotEmpty { calculate(it) }

?

Can it be implemented as a dsl tho?

Just wondering, what is the rationale for the

get

operator returning

Nullable?

types for Maps but not for Lists? I understand that in a map, you may not know whether the key is set. But in a List, you may not know whether the index exists (i.e. the list is long enough) either??!

How can I write a lambda with a receiver such that I can write the following style DSL

createHttpServer {
            options = myServerOptionsObjectVariableFromAboveSomewhere
            port = 8080
        }

which should run effectively

vertx().createHttpServer(options).listen(port)

?

Why does Kotlin have both

Exception

and

RuntimeException

? I can sort of see a compatibility argument but both are present even in common

Here's a question for the language designers: On on hand kotlins collections have extensions like

toList

or

toMap

. On the other hand

asSequence

and

asIterable

. From my testing the

to

methods copy the collection where the

as

methods create views on the data. Which means if the collections changes, the views also have access to the mutated data. Is this a not documented rule? Would it be "wrong" if one of my own

asCustomList

copies the data instead of creating a view? Should I call it

toCustomList

?

Or I have to use pure Java annotation in this case, since it feels like Annotation Processor doesn't understand

KClass<*>

is it by design that fold and foldRight have the order of accumulator and current value switched?

Is there a stdlib way to consecutively apply a list of functions to a single variable and their outputs?

Any ideas on what infix functions can be useful in a rest api? Looking for ideas to codify

Do you guys know if there's any particular reason for

Char.isDigit

to not have it's opposite

Char.isNotDigit

?

is there a simple way to window a

Sequence

based on attributes of the data? for example, if i have

sequenceOf(1,2,3,5,6,8,10,14,15)

i'd like to "merge" contiguous elements together into a sequence that is

sequenceOf([1,2,3], [5,6], [8], [10], [14,15])

i'd like to retain the lazy evaluation, such that

[1,2,3]

is yielded only when it is needed