Iteration of the list Stepping through the elements, perhaps as in map . As we design various kinds of lists, we may choose different subsets of these operations, and fill in more details. We'll consider three different ones. After a high-level overview, we'll return to each in more detail. The simplest lists simply provide the linear structure, but with no user control over that structure.
Iteration provides access to the elements.
The list cannot rearrange itself unless elements are added or removed. We add some complexity and usefulness by giving the user some control over where elements go in the list. Such lists might be called sequenced lists . Insertion and deletion ensure that the sort order is maintained. Both lists and arrays provide mechanisms for collecting information.