The 'aref' function returns the specified element out of a previously
created array. Array elements may be any valid lisp data type, including
lists or arrays. Arrays made by make-array and
accessed by 'aref' are 
(setq my-array '#(0 1 2 3 4))       => #(0 1 2 3 4)
(aref my-array 0)                   => 0
(aref my-array 4)                   => 4
(aref my-array 5)                   => error: array index out of bounds - 5
my-array                            => #(0 1 2 3 4)
                                    
(setq new (make-array 4))           => #(NIL NIL NIL NIL)
(setf (aref new 0) (make-array 4))  => #(NIL NIL NIL NIL)
new                                 => #(#(NIL NIL NIL NIL) NIL NIL NIL) 
(setf (aref (aref new 0) 1) 'a)     => A
new                                 => #(#(NIL A NIL NIL) NIL NIL NIL)
(setf (aref new 2) '(a b c))        => (A B C)
new                                 => #(#(NIL A NIL NIL) NIL (A B C) NIL)
Read macro: There is a built-in read-macro for arrays,
Note: This function returns the value of an array element.
However, there is no equivalent direct function to set the value of an array
element to some value. 
See also: