Scala example source code file (STTest.scala)

This example Scala source code file (STTest.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.

Learn more about this Scala project at its project page.

Java - Scala tags/keywords

boolean, forall, forallst, int, list, speclite, starray, stref, sttest

The STTest.scala Scala example source code

package scalaz
package effect

import std.AllInstances._
import ST._

object STTest extends SpecLite {
  type ForallST[A] = Forall[ST[?, A]]

  "STRef" in {
    def e1[S] = for {
      x <- newVar[S](0)
      r <- x mod {_ + 1}
    } yield x
    def e2[S]: ST[S, Int] = for {
      x <- e1[S]
      r <- x.read
    } yield r
    runST(new ForallST[Int] { def apply[S] = e2[S] }) must_===(1)
  }

  "STArray" in {
    def e1[S] = for {
      arr <- newArr[S, Boolean](3, true)
      _ <- arr.write(0, false)
      r <- arr.freeze
    } yield r
    runST(new ForallST[ImmutableArray[Boolean]] { def apply[S] = e1[S] }).toList must_===(
      List(false, true, true))
  }
}