CODEWITHSUNDEEP
scalasyntax
blauerschluessel
blauerschluessel

Reputation: 183

How to bypass for & yield in Scala for a certain function?

I have written the following Scala code:

  case class A(x: Int, out: List[Int])

  def isIn: Int => List[Int] => Boolean =
    x => l => l.filter { _ == x }.nonEmpty

  def filterTest4: (Int, List[A]) => List[List[Int]] = (x, a) =>
    for (l <- a; if (isIn(x)(l.out))) yield l.out

The functrion filterTest4 works perfectly fine, however uses the for & yield, which I do not really like and thus would like to see another way. I would be very happy, if someone offered a constructive comment / answer. Please be nice and keep in mind I just started writing in Scala maybe 3 days ago.

Upvotes: 0

Views: 86

Answers (2)

Gabriele Petronella
Gabriele Petronella

Reputation: 108159

Alternatively, as other suggested, you can use collect, which combines map and filter. Also you can destructure the case class to access out directly.

def filterTest5: (Int, List[A]) => List[List[Int]] = (x, a) => a.collect {
  case A(_, out) if isIn(x)(out) => out
}

Upvotes: 1

blauerschluessel
blauerschluessel

Reputation: 183

I just found the map function, which could be used like this: 

 def filterTest5: (Int, List[A]) => List[List[Int]] = (x, a) =>
    a.filter { a2 => isIn(x)(a2.out) }.map { a2 => a2.out }

I think that does the job.

Upvotes: 1

Related Questions