Scala Programming Projects

Usage examples

Cats provide several derivations of the Semigroup type class. It also declares a |+| operator in SemigroupOps, which is an alias for combine.

Some examples are as follows:

import cats.implicits._
1 |+| 2
// res0: Int = 3
"Hello " |+| "World !"
// res1: String = Hello World !
(1, 2, "Hello ") |+| (2, 4, "World !")
// res2: (Int, Int, String) = (3,6,Hello World !)

Thanks to the built-in derivations brought up with import cats.implicits._, we can combine Int, String, Tuple2, and Tuple3.

We can also combine some parameterized types, such as Option and Vector:

Vector(1, 2) |+| Vector(3, 4)
// res3: Vector[Int] = Vector(1, 2, 3, 4)
Option(1) |+| Option(2)
// res4: Option[Int] = Some(3)
Option(1) |+|  None |+| Option(2)
// res5: Option[Int] ...