Simple singly linked list using data classes in Kotlin using one line. Featuring data classes and null safety

simple-linked-list-data-class.kt

// Linked list
data class Node<T>(var value: T, var next: Node<T>?);

fun main() {
  val head = Node(1, null)
  val second = Node(2, Node(3, null))   // two more (init multiple)
  head.next = second
  
  println(head.value)                   // 1
  println(head.next?.value)             // 2
  println(head.next?.next?.value)       // 3
  println(head.next?.next?.next?.value) // null
  
  println(head)                         
  // Node(value=1, next=Node(value=2, next=Node(value=3, next=null)))
}

You can easily add functions, iterators, whatever you want pretty easily. For example here is reduce

data class Node<T>(var value: T, var next: Node<T>?) {
  fun reduce(op: (acc: T, item: T) -> T): T {
    var result = value
    var node = next
    while(node != null) {
      result = op(result, node.value)
      node = node.next
    }
    
    return result
  }
}

...

val head = Node(1, null)
val second = Node(2, Node(3, null))  
head.next = second
val product = head.reduce {acc, item -> acc * item}
println(product)  // 6

MIT License