split

fun <A> Iterable<A>.split(): Pair<List<A>, A>?(source)

Attempt to split the Iterable into the tail and the first element. Returns null if the Iterable is empty, otherwise returns a Pair of the tail and the first element.

import arrow.core.*
import io.kotest.matchers.shouldBe

fun test() {
  emptyList<Int>().split() shouldBe null
  listOf("A", "B", "C").split() shouldBe Pair(listOf("B", "C"), "A")
}

fun <A> Sequence<A>.split(): Pair<Sequence<A>, A>?(source)

attempt to split the computation, giving access to the first result.

import arrow.core.split
import io.kotest.matchers.shouldBe

fun test() {
  sequenceOf("A", "B", "C").split()?.let { (tail, head) ->
    head shouldBe "A"
    tail.toList() shouldBe listOf("B", "C")
  }
  emptySequence<String>().split() shouldBe null
}