Examples of semi group from http://inoio.de/blog/2014/07/19/type-class-101-semigroup/

semigroup.sc

// following http://inoio.de/blog/2014/07/19/type-class-101-semigroup/

trait Semigroup[A] {
  def append(a: A, b: A): A
}

implicit val intSemigroup = new Semigroup[Int] {
  def append(a: Int, b: Int) = a + b
}

object Semigroup {
  def apply[A](implicit F: Semigroup[A]) = F
}

Semigroup.apply[Int].append(1, 2)

Semigroup[Int].append(1, 2)

// shorter form

trait SemigroupSyntax[A] {
  def self: A

  def F: Semigroup[A]

  def |+|(b: A): A = append(b)

  // alias for append
  def append(b: A): A = F.append(self, b)
}

implicit def ToSemigroupOps[A: Semigroup](a: A): SemigroupSyntax[A] =
  new SemigroupSyntax[A] {
    def self: A = a

    def F: Semigroup[A] = implicitly[Semigroup[A]]
  }
/* or alternatively a more lengthy form without using 'implicitly', for instance,
 *
 *    implicit def ToSemigroupOps[A](a: A)(implicit ev:Semigroup[A]): SemigroupSyntax[A] =
 *     new SemigroupSyntax[A] {
 *       def self: A = a
 *       def F: Semigroup[A] = ev
 *     }
 */

3 |+| 4   // 7

implicit def optionInstances[A: Semigroup] = new Semigroup[Option[A]] {
  def append(a: Option[A], b: Option[A]): Option[A] = {
    (a, b) match {
      case (Some(a1), Some(b1)) => Some(Semigroup[A].append(a1, b1))
      case (Some(_), None) => a
      case (None, Some(_)) => b
      case _ => None
    }
  }
}

Option(30).append(Option(40)) == (Option(30) |+| Option(40))  // true; both equals to Option(70)