Cats SemigroupK vs Semigroup

CatsSemigroupK.scala

import cats._
import cats.implicits._


// Cats SemigroupK vs Semigroup

object CatsSemigroupK extends App {

  // semigroupK doesn't care about contents

  val semListK=SemigroupK[List]

  val li=List(1,2,3)
  val li2=List(100,200)

  println(semListK.combineK(li,li2))

  val semOptionK=SemigroupK[Option]

  // picks first not failing value
  println(semOptionK.combineK(23.some, 100.some))
  println(semOptionK.combineK(24.some, None))
  println(semOptionK.combineK(None, 12.some))

  // sum returns Option[Either[A,B]]

  println(semOptionK.sum(25.some, 1000.some))
  println(semOptionK.sum(None, 1000.some))
  println(semOptionK.sum(None, None))

  // vs semigroup, we care about contents

  val semOption=Semigroup[Option[Int]]

  // combines
  println("Semigroup")
  println(semOption.combine(26.some, 100.some))
  println(semOption.combine(27.some, None))
  println(semOption.combine(None, 12.some))

}

output.txt

List(1, 2, 3, 100, 200)
Some(23)
Some(24)
Some(12)
Some(Left(25))
Some(Right(1000))
None
Semigroup
Some(126)
Some(27)
Some(12)