Flow.last() operator

I found myself often doing this flow.toList().last() usually for code that works with Flow which represents progress, when I want to receive the final item, it would be complimentary to first()/single() item

It also can be replaced with something like

flow
   .filterInInstance<SomeTerminalItemType>()
   .single()

but it’s not always so simple, for example, a sealed hierarchy may have a few terminal types for operation

Reactive libraries have such operator http://reactivex.io/documentation/operators/last.html

[fvasco]

Hi, @gildor, you need a Flow with a state, strictly speaking on this you case, you should prefer a Deferred (or a CompletableStateFlow, which looks very ugly).

I am not suggesting you to use a Deferred instead of Flow, I am considering that a deferred task should put its result in a Deferred.

[fvasco]

We got the same issue, we elaborate a sequence of event and have to get the last one.

Unfortunately, we require a suspend fun inside a filter { }, so we have to switch to Flow, but last is missing.

Here our patch:

public suspend fun <T> Flow<T>.last(): T? = reduce { _, value -> value }
public suspend fun <T> Flow<T>.lastOrNull(): T? = fold<T?, T?>(null) { _, value -> value }