For convenience the same operations can be applied to arrays as well as to lists. However, size affecting operations are more costly when using arrays.
L is treated as the right hand side of an assignment.
If L is empty, the NULL expression is returned. L is treated as the right hand side of an assignment. A subrange can be extracted from a given list. The index can be any expression that evaluates to an integer value. See also the less and sort commands of the user module.