SimpleArray

What it is

The Lisp SimpleArray type is an array that is not displaced to another array. It has no fill pointer and it is not adjustable.

A SimpleArray is an array, thus the SimpleArray type is a subtype of LispArray, and implements all the functions that LispArray implements, except in the case of the fill pointer and dynamic adjustment of its size.

The SimpleArray type has the disjoint subtypes SimpleVector, SimpleString, and SimpleBitVector.

What it means

As it says above, a SimpleArray is an array that is not displaced to another array. What this means in practice is that a SimpleArray is the Lisp analogue to the sort of generic multi-dimensional array you would find in a language like Java or Perl. It isn't adjustable, which means that once created, the dimensions of a SimpleArray cannot be modified. It is never displaced onto another array.

Implementation, or how it's done

The SimpleArray type will be implemented as an interface in the lisp.common.type package (as are the rest of the Lisp types in CLforJava.) New instances of SimpleArray will be created using a Factory class. Backing store will be a native Java array. Note that a SimpleArray can never share the backing store of another array.

All Lisp functions that operate on LispArray should operate identically on SimpleArray, save in the following cases:

References

StringsAndArrays

HyperSpec	CLtL
CLHS: Type SIMPLE-ARRAY	2.5 - Arrays

Discussions

SimpleArray discussion on the Forum

-- KitPeters - 05 Oct 2005