Playing With Scala - Writing Function : Flatten

Few weeks ago since now :) I started participating in a course ‘Functional Programming Principles in Scala’ by Martin Odersky. I have already completed 4 weeks (course consists of 6 weeks) and I can tell honestly that this is the best course I’ve ever been doing.

My knowledge about scala is still increasing !

Below you can find a sample of what I can now do. The problem is to implement function flatten(xs: List[Any]): List[Any] which takes a list of anything an tries to flatten it. For example

flatten(List(List(1, 1), 2, List(3, List(5, 8))))

should return a following list

List[Any] = List(1, 1, 2, 3, 5, 8)

/** * Created by ssledz on 25.07.16. */ object Flatten { def flatten(xs: List[Any]): List[Any] = xs match { case List() => Nil case y :: ys => { y match { case z: List[Any] => flatten(z) case _ => List(y) } } ::: flatten(ys) case _ => List(xs) } def main(args: Array[String]) { List( flatten(List(List(1, 1), 2, List(3, List(5, 8)))), flatten(List(1, 2, 3)), flatten(List(List(1, 2), 3, List(4))), flatten(List(List(List(List(1, 2), 3, List(4))), List(5, 6, 7))) ) foreach println } }

At the end I would like to say ‘thank you’ to Atlassian company for paying a half for this course !

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Everything should be made as simple as possible, but no simpler.

Playing With Scala - Writing Function : Flatten

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