Scala example source code file (NewTypeUsage.scala)

This example Scala source code file (NewTypeUsage.scala) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Scala by Example" ^TM.

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Java - Scala tags/keywords

app, conjunction, disjunction, list, newtypeusage, tags

The NewTypeUsage.scala Scala example source code

package scalaz.example

object NewTypeUsage extends App {

  import scalaz._
  import std.anyVal.{booleanInstance, booleanDisjunctionNewTypeInstance, booleanConjunctionNewTypeInstance}
  import Tags.{Conjunction, Disjunction}
  import std.list.listInstance

  assert(!booleanInstance.disjunction.zero)
  assert(booleanInstance.conjunction.zero)

  assert(!Tag.unwrap(Monoid[Boolean @@ Disjunction].zero))
  assert(Tag.unwrap(Monoid[Boolean @@ Conjunction].zero))

  val bools = List(true, false)

  val boolDisjunctions: List[Boolean @@ Disjunction] = Tag.subst(bools)
  assert(Tag.unwrap(listInstance.fold(boolDisjunctions)))

  val boolConjunctions: List[Boolean @@ Conjunction] = Tag.subst(bools)
  assert(!Tag.unwrap(listInstance.fold(boolConjunctions)))
}