While learning about functional programming the simple sieve example was brought up in Haskell. I wanted to try a Kotlin implementation using sequences.

Are there any other quick wins without modifying the structure too much?

import kotlin.coroutines.experimental.buildSequence import kotlin.system.measureTimeMillis  fun sieve(isPrime: Int, ints: Sequence<Int>): Boolean = with(ints.first()){     return when {         isPrime  < 2 -> false         isPrime == 2 -> true         isPrime == this -> true         isPrime.rem(2) == 0 -> false //        isPrime.and(1) == 0 -> false // same way to check if number is even         this > isPrime -> false         else -> sieve(isPrime, ints.filter { n -> n.rem(this) != 0 })     } }  fun main(args: Array<String>) {     val lazySeq = buildSequence { for (i in 3..Int.MAX_VALUE step 2) yield(i) }     println("Duration = $  {measureTimeMillis { println("isPrime(4057) = $  {sieve(4057, lazySeq)}") }}ms") //    (2..200).forEach { println("isPrime($  it) = $  {sieve(it, lazySeq)}") } }