Scala iterator.count for large lists (>int32 size)-CodePudding

I have large lists that I need to get the size of. Count returns an int, according to the scala api https://www.scala-lang.org/api/2.13.3/scala/collection/immutable/List.html, which may overflow on large lists.

How do I get around this?

CodePudding user response：

A solution could be:

aList.foldLeft(0L)((acc, _) => acc   1)

This will return the total number of elements as a Long number. If you want, you can wrap this functionality with the Pimp my library pattern:

implicit class LongList[A](list: List[A]) {
  def sizeL: Long = list.foldLeft(0L)((acc, _) => acc   1)
}

As underlying in the comments, this operation will cost you O(n), so if you have other alternatives try to explore them :)