Scala3

def hash(s: String): Long = s.foldLeft(0)((h, c) => (h + c)*17 % 256)

extension [A] (a: List[A])
    def mapAtIndex(idx: Long, f: A => A): List[A] =
        a.zipWithIndex.map((e, i) => if i == idx then f(e) else e)

def runProcedure(steps: List[String]): Long =
    @tailrec def go(boxes: List[List[(String, Int)]], steps: List[String]): List[List[(String, Int)]] =
        steps match
            case s"$label-" :: t =>
                go(boxes.mapAtIndex(hash(label), _.filter(_._1 != label)), t)
            case s"$label=$f" :: t =>
                go(boxes.mapAtIndex(hash(label), b => 
                    val slot = b.map(_._1).indexOf(label)
                    if slot != -1 then b.mapAtIndex(slot, (l, _) => (l, f.toInt)) else (label, f.toInt) :: b
                ), t)
            case _ => boxes
    
    go(List.fill(256)(List()), steps).zipWithIndex.map((b, i) =>
        b.zipWithIndex.map((lens, ilens) => (1 + i) * (b.size - ilens) * lens._2).sum
    ).sum

def task1(a: List[String]): Long = a.head.split(",").map(hash).sum
def task2(a: List[String]): Long = runProcedure(a.head.split(",").toList)