Questionable use of Scalaz Memo

scalazMemo.scala

object FlakyFunctionTest {

  import scalaz._
  import Scalaz._

  var state = false

  val function: Unit => String = scalaz.Memo.immutableHashMapMemo { _ =>
    println(s"We received a call")

    if(!state) {
      state = true
      throw new RuntimeException("Oops, try again later")
    }

    s"Returning from this method"
  }
}

scala> FlakyFunctionTest.function(())
We received a call
java.lang.RuntimeException: Oops, try again later
  at MemoTest$$anonfun$1.apply(<console>:39)
  at MemoTest$$anonfun$1.apply(<console>:34)
  at scalaz.MemoFunctions$$anonfun$immutableMapMemo$1$$anonfun$apply$4$$anonfun$apply$5.apply(Memo.scala:89)
  at scala.Option.getOrElse(Option.scala:120)
  at scalaz.MemoFunctions$$anonfun$immutableMapMemo$1$$anonfun$apply$4.apply(Memo.scala:88)
  ... 43 elided

scala> FlakyFunctionTest.function(())
We received a call
res57: String = Returning from this method

scala> FlakyFunctionTest.function(())
res58: String = Returning from this method