arrow-core-data / arrow.core / kotlin.sequences.Sequence / ifThen

ifThen

fun <A, B> Sequence<A>.ifThen(fb: Sequence<B>, ffa: (A) -> Sequence<B>): Sequence<B>

Logical conditional. The equivalent of Prolog’s soft-cut. If its first argument succeeds at all, then the results will be fed into the success branch. Otherwise, the failure branch is taken.

import arrow.core.ifThen

fun main(args: Array<String>) {
  //sampleStart
  val result =
   sequenceOf(1,2,3).ifThen(sequenceOf("empty")) { i ->
     sequenceOf("$i, ${i + 1}")
   }
  //sampleEnd
  println(result.toList())
}