Reactive Programming in Kotlin

Accumulating emissions – reduce operator

Reduce is a perfect accumulation operator. It accumulates all the emissions by the producer and emits them once it receives the onComplete notification from the producer.

Here is an example:

    fun main(args: Array<String>) { 
      Observable.range(1,10) 
      .reduce { previousAccumulation, newEmission ->        previousAccumulation+newEmission  } 
      .subscribeBy { println("accumulation $it") } 
 
       Observable.range(1,5) 
       .reduce { previousAccumulation, newEmission ->         previousAccumulation*10+newEmission  } 
       .subscribeBy { println("accumulation $it") } 
      } 

The output is shown as follows:

The reduce operator works similar to the