Array is a built-in function.  Given a (short) integer n, and a component
type T, it returns the type of arrays of T which can be indexed by
integers between 0 and n-1.  A period is used to indicate subscription.
It has signature:

    Array: func [size: val Short; comptype: type {New; V}]
                type A {. : func [var A; val Short] var comptype;
                        . : func [val A; val Short] val comptype;
			New; V;
			size: func [] val Short;
		       };

The size operation always returns the number of elements in the array,
i.e. the first argument to the Array function.

Implementation note:  New and V can be SLOW.  They may involve explicit calls
to the corresponding operations of the component type.  Note however that
V does not get used for component-wise array operations.  Subscript
checks are inserted by the compiler, but removed by the optimizer.