Friends, I had a great time trying to implement `s...

# codereview

[Paulo Cereda]

Friends, I had a great time trying to implement sleepsort in Kotlin. 😁 The best I could come up with is as follows (playground link):

import kotlinx.coroutines.coroutineScope
import kotlinx.coroutines.delay
import kotlinx.coroutines.async
import kotlinx.coroutines.awaitAll

suspend fun main() {
    println(sleepsort(listOf(63, 32, 62, 14, 5)))
}

suspend fun sleepsort(list: List<Int>): List<Int> = coroutineScope {
    buildList {
        list.map { number ->
            async {
                delay(number.toLong())
                add(number)
            }
        }.awaitAll()
    }
}

Do you have any suggestions and/or improvements to make it better (or even worse)? Thank you so much, and season's greetings to everyone! 🎄

[Joffrey]

You don't need `async`'s result, so you can use launch instead. Then you also don't need awaitAll() (or rather joinAll() once you replaced async with launch), because coroutineScope will wait for it's children. You will have to move it inside buildList though.

[Paulo Cereda]

Thanks Joffrey, it works like a charm! gratitude thank you

[Joffrey]

Also, your list is not thread safe. It works in this case because there is only one thread, but if such a function were called in a context with a multi-threaded dispatcher, it might not work properly. You might need to guard it with a mutex or limit parallelism

[Robert Williams]

Since you asked for worse versions, here's one that entirely uses flows blob stuck out tongue :

suspend fun sleepsort(list: List<Int>): List<Int> =
        list.asFlow().map { number ->
            flow {
                delay(number.toLong())
                emit(number)
            }
        }.flattenMerge(list.size).toList()