Scala structural types with generics

In Scala, if you want to use structural types with a generic class, you must cast the instance to the structural type and import reflective calls.

Because we have to cast the instance to another type, it is better to define the type alias in a companion object.

import ExampleTest.CanAddElement

import scala.language.reflectiveCalls
import org.scalatest.{FlatSpec, Matchers}

object ExampleTest {
  type CanAddElement = {def add(s: Any): Boolean}
}

class ExampleTest extends FlatSpec with Matchers {
  it should "add an element to the container" in {
    def add[T](container: CanAddElement)(element: T): Unit = {
      container.add(element)
    }

    val set = new java.util.HashSet[String]()
    add(set.asInstanceOf[CanAddElement])("3")
    set.contains("3") shouldEqual true

    val list = new java.util.LinkedList[String]()
    add(list.asInstanceOf[CanAddElement])("3")
    list.contains("3") shouldEqual true
  }
}
Older post

Visualize common elements of two datasets using NetworkX

How to use undirected graph to visualize common elements of two Pandas data frames

Newer post

Word cloud from a Pandas data frame

Create a nice visualization of the most popular words in your data frame