CODEWITHSUNDEEP
scalafunctional-programming
f23aaz
f23aaz

Reputation: 339

Can't get single values from tuple taken from Option[Double]

Hey I'm having difficulty with getting values from a tuple

I want to do arithmetic operations on the values of two Option[Double] if they are not equal to None. The code I have so far is this

def optionDoubleAddition(a: Option[Double], b: Option[Double]) : Option[Double] = {

  val tuple = if(a != None && b != None) (a.getOrElse(0: Double),b.getOrElse(0: Double))
  println(tuple) //prints the values correctly when passed two doubles
  None //something to make the function work
}

It won't allow me to get the single elements from the tuple with either

println(t(0))
println(t._1)

Also I'm a bit concerned with the getOrElse function is there any alternative to this, i've tried solving the above in different ways for example if i wanted to do the following

val example: Option[Double] = Some(5.0)

and I want to get the value of example or None otherwise

example.getOrElse(None)

which returns the value as Any however I need it to be a double, if i try the following I also run into errors if it is None

val doubleValue: Double = example.getOrElse(None)

Thanks!

Upvotes: 0

Views: 71

Answers (1)

jwvh
jwvh

Reputation: 51271

I think this is what you're looking for, at least it is correct for the method profile.

def optionDoubleAddition(a: Option[Double], b: Option[Double]) : Option[Double] =
  for {x <- a; y <- b} yield x+y

This unwraps each Option, adds them, and re-wraps the result, but if either or both is None then the unwrapping stops and None is returned.

Upvotes: 3

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