Question

I’m looking for a way to treat an Any as an Array or Seq and iterate over it, if possible.

Currently I have some code that looks like this, taking a sequence of Any’s and flattening out any Traversable or Array objects contained.

def flattenAsStrings(as: Seq[Any]): Seq[String] = {
  val (travValued, other) = as.partition(a => classOf[Traversable[_]] isAssignableFrom(a.getClass))
  val (arrayValued, singleValued) = other.partition(a => a.isInstanceOf[Array[_]])
  val travStrings = travValued.map(_.asInstanceOf[Traversable[_]].map(_.toString)).flatMap(_.toList)
  val arrayStrings = arrayValued.map(_.asInstanceOf[Array[_]].map(_.toString)).flatMap(_.toList)
  singleValued.map(_.toString) ++ travStrings ++ arrayStrings
} 

It feels like there mustr be a simpler way to do this in Scala, given implicit conversions and whatnot. Anyone?

Answer 1

Basically you want to force each element to a Seq, and then flatten them all at once. Array has an implicit conversion to Seq and both Seq and Traversable have a .toSeq method. So we can do:

val t: Traversable[Int] = List(1, 2, 3)
val a: Array[Int] = Array(4, 5, 6)
val other = "whatever"
val as: Seq[Any] = List(t, a, other)

as.flatMap{
  case t: Traversable[_] => t.toSeq
  case a: Array[_] => a.toSeq
  case other => Seq(other)
}.map{_.toString}
//Seq[java.lang.String] = List(1, 2, 3, 4, 5, 6, whatever)

(as an aside, this is pretty ugly Scala code, you might want to consider refactoring things to get rid of using a Seq[Any] in the first place)