Is Kotlin Flow’s Collect is only internal kotlinx.coroutines API?

The answer is, NO, collect is not only internal kotlinx.coroutines API. The error message is misleading.

As per @ir42’s comment, add import kotlinx.coroutines.flow.collect solve the problem.

Additional info, why I didn’t pick collectLatest as the answer

collect and collectLatest is different.

Using this example

fun simple(): Flow<Int> = flow { // flow builder
    for (i in 1..3) {
        delay(100) // pretend we are doing something useful here
        emit(i) // emit next value
    }
}

fun main() = runBlocking<Unit> {
    // Launch a concurrent coroutine to check if the main thread is blocked
    launch {
        for (k in 1..3) {
            println("I'm not blocked $k")
            delay(100)
        }
    }
    // Collect the flow
    simple().collect { value -> println(value) } 
}

Collect will produce

I'm not blocked 1
1
I'm not blocked 2
2
I'm not blocked 3
3

as per https://kotlinlang.org/docs/reference/coroutines/flow.html

But collectLatest

fun simple(): Flow<Int> = flow { // flow builder
    for (i in 1..3) {
        delay(100) // pretend we are doing something useful here
        emit(i) // emit next value
    }
}

fun main() = runBlocking<Unit> {
    // Launch a concurrent coroutine to check if the main thread is blocked
    launch {
        for (k in 1..3) {
            println("I'm not blocked $k")
            delay(100)
        }
    }
    // Collect the flow
    simple().collectLatest { value -> println(value) } 
}

will produce

I'm not blocked 1
I'm not blocked 2
1
I'm not blocked 3
2