Scala returning option value

Question

The problem is that I'd like this function to return option value (in form of Option[None]) or Option[something], but it only returns a Unit. What am I missing?

  def intersection(another: Interval){
     var test: Option[Interval] = None
    if (this.isLaterThan(another) || another.isLaterThan(this)){
       test
    }
     else {
       val a = this.start.later(another.start)
       val b = this.end.earlier(another.end)
       test=Some(new Interval(a, b))
       test
       
     }

score 1 · Answer 1 · answered Sep 20 '17 at 06:13

you should specify the type it return

def intersection(another: Interval): Option[Interval] = {
    if (this.isLaterThan(another) || another.isLaterThan(this)){
       None
    }
     else {
       val a = this.start.later(another.start)
       val b = this.end.earlier(another.end)
       Some(new Interval(a, b))

     }
}

try not to use var in scala I change the code a bit

score 1 · Accepted Answer · answered Sep 20 '17 at 07:05

1

You are missing = before the first {. Methods defined without = always return Unit. Note that this syntax is actually deprecated precisely because this is a common error: https://issues.scala-lang.org/browse/SI-7605.

answered Sep 20 '17 at 07:05

Alexey Romanov

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Scala returning option value

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