3.3.1 Linear Linked List function

[kenshih1989]

Was having few question regarding following functions:

1. Confusing functions name
   The following 2 functions name quite confusing:

setNextNode<-function(llist){
  llist$nextnode
}
setNextElement<-function(llist){
  llist$element
}

The contents in those function were showing the nextnode and element of a linked list node.
Why need use "set" instead of show?
Some more, "showElement" instead of "setNextElement" would be better since it is showing the element?

2. Unable to add element

addElement<-function(new, llist) 
{
  if (isEmpty(llist)) {
    llist<-linkedlist(new)
  } else
  {
    llist<-linkListNode(llist, new)
  }
  llist
}

linkListNode <- function(val, node=NULL) {
  llist <- new.env(parent=create_emptyenv())
  llist$element <- val
  llist$nextnode <- node
  class(llist) <- "linkList"
  llist
}

From the source code provided, I could not find a function call "linkedlist" ?
If the list is not empty, the previous list become a new element and "new" become next node?