How can this be rewritten in a better way wrt structured concurrency and flow etc ``` fun <A, B&...

# coroutines

[rrva]

How can this be rewritten in a better way wrt structured concurrency and flow etc

fun <A, B> Iterable<A>.parallelMap(context: CoroutineContext, f: suspend (A) -> B): List<B> = runBlocking {
    map { async(context) { f(it) } }.map { it.await() }
}

@OptIn(ExperimentalCoroutinesApi::class)
private val apiPool = Dispatchers.IO.limitedParallelism(10)

val results = foo.parallelMap(apiPool) { fetchStuffFromRestAPI(it.id) }

[Sam]

For structured concurrency it would be best to change the parallelMap function to a suspend function:

suspend fun <A, B> Iterable<A>.parallelMap(f: suspend (A) -> B): List<B> = coroutineScope {
    map { async { f(it) } }.map { it.await() }
}

[Sam]

I wouldn’t introduce flows here; I don’t think it would help you

[Sam]

You could also swap .map { it.await() } for .awaitAll() which will fail fast if one of the child jobs fails — depends on your approach to the structured concurrency

[rrva]

if I want to convert failures to
null, just try-catch inside the lambda is cleanest?

[Sam]

Yes 👍