Merge Flow operator is missing

The merge() operator is missing

fun Flow<T>.merge(vararg flows: Flow<T>): Flow<T> = TODO()

Use Case

Representing clicks on a keypad:

val key1: View
val key2: View
val numberClicks: Flow<Int> = merge(
  key1.clicks().map { 1 },
  key2.clicks().map { 2 }
)

Note: I think fun Flow<T>.merge(otherFlow: Flow<T>): Flow<T> is an anti-pattern because it creates hard to read flows, so I am intentionally not requesting it 😛

[elizarov]

flattenMerge is in preview, because it has an optional concurrency parameter and we have not decided yet what exactly to do with it and with other “concurrent” operators (see #1147). In particular it means that if you are planning to use the above merge implementation with more than 16 flows, then you should rewrite it like this:

fun <T> merge(vararg flows: Flow<T>): Flow<T> = 
    flowOf(*flows).flattenMerge(concurrency = flows.length)

[elizarov]

The “gotcha” with concurrency limit is a strong motivator for a separate merge operator.