Kotlin - Debounce Only One Specific Value When Emitting from Flow - kotlin

Question

I have two flows that are being combined to transform the flows into a single flow. One of the flows has a backing data set that emits much faster than the the other.
Flow A - emits every 200 ms
Flow B - emits every ~1s
The problem I am trying to fix is this one:
combine(flowA, flowB) { flowAValue, flowBValue // just booleans
flowAValue && flowBValue
}.collect {
if(it) {
doSomething
}
}
Because Flow A emits extremely quickly, the boolean that's emitted can get cleared rapidly, which means that when flowB emits true, flowA already emitted true and the state is now false.
I've attempted something like:
suspend fun main() {
flowA.debounce {
if (it) {
1250L
} else {
0L
}
}.collect {
println(it)
}
}
But this doesn't work as sometimes the true values aren't emitted - inverting the conditional (so that if(true) = 0L else 1250L) also doesn't work. Basically what I'm looking for is that if flowA is true - hold that value for 1 second before changing values. Is something like that possible?

Answer 1

I made this use conflated on the 2nd flow, that is drastically faster, so that zipping them will always take the latest value from fastFlow, when slowFlow is finally ready, if you don't use conflated on the 2nd flow, it will always be the first time both emit.
fun forFlow() = runTest {
val slowString = listOf("first", "second", "third", "fourth")
val slowFlow = flow {
slowString.forEach {
delay(100)
emit(it)
}
}
val fastFlow = flow {
(1 until 1000).forEach { num ->
delay(5)
emit(num)
}
}.conflate()
suspend fun zip() {
slowFlow.zip(fastFlow) { first, second -> "$first: $second" }
.collect {
println(it)
}
}
runBlocking {
zip()
}
println("Done!")
}
With Conflated on fastFlow:
first: 1
second: 15
third: 32
fourth: 49
Done!
Without Conflated on fastFlow:
first: 1
second: 2
third: 3
fourth: 4
Done!