Is there a way to compare changes between emissions? Example: ```flowOf(1,2,5) .operation { last, ...

# coroutines

[Dragos Rachieru]

Is there a way to compare changes between emissions?
Example:

flowOf(1,2,5)
  .operation { last, current -> current - last }
  .onEach { println(it) }
  .collect()

Result: 1,3

[ephemient]

https://github.com/Kotlin/kotlinx.coroutines/issues/1767

[bezrukov]

it's possible via scan (use Pair<Int, Int> as an accumulator), but easier to write your own zipWithNext function, it's pretty simple

[Dragos Rachieru]

Thank you

[Lukas Lechner]

What about .reduce() or fold()? With those you also have access to the previous and the current value.

[ephemient]

fold is similar to scan, so you need to provide an initial value. reduce throws if the flow was empty. those might work for Dragos, depends on the situation though

[Dragos Rachieru]

I want to emit these values further, i think I can put them in a list of lists and then send them further