これが私がそれを行う方法です:
class ListTests extends FunSuite {
test("The three lists from his example") {
val l1 = List("a", "b", "c")
val l2 = List(1, 2, 3, 4)
val l3 = List("+", "#", "*", "§", "%")
// All lists together
val l = List(l1, l2, l3)
// Max length of a list (to pad the shorter ones)
val maxLen = l.map(_.size).max
// Wrap the elements in Option and pad with None
val padded = l.map { list => list.map(Some(_)) ++ Stream.continually(None).take(maxLen - list.size) }
// Transpose
val trans = padded.transpose
// Flatten the lists then flatten the options
val result = trans.flatten.flatten
// Viola
assert(List("a", 1, "+", "b", 2, "#", "c", 3, "*", 4, "§", "%") === result)
}
}