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ANSI Common Lisp  15 Arrays 15.2 Dictionary of Arrays
| 15.2.1 array |
System Class |
- Class Precedence List:
-
array,
t
- Description:
-
An array contains objects arranged according to a
Cartesian coordinate system.
An array provides mappings from a set of
fixnums
{i0,i1,...,ir-1} to corresponding elements
of the array,
where 0 <= ij < dj,
r is the rank of the array, and dj is the size of dimension j of
the array.
When an array is created, the program requesting its creation may
declare that all elements are of a particular type,
called the expressed array element type.
The implementation is permitted to upgrade this type in order to
produce the actual array element type,
which is the element type for the array is actually specialized.
See the function upgraded-array-element-type.
- Compound Type Specifier Kind:
-
Specializing.
- Compound Type Specifier Syntax:
-
(array [{element-type | *} [dimension-spec]])
dimension-spec::= rank | * | ({dimension | *}*)
- Compound Type Specifier Arguments:
-
dimension - a valid array dimension.
element-type - a type specifier.
rank - a non-negative fixnum.
- Compound Type Specifier Description:
-
This denotes the set of arrays whose
element type, rank, and dimensions
match any given
element-type, rank, and dimensions.
Specifically:
If element-type is the symbol *,
arrays are not excluded on the basis of their element type.
Otherwise, only those arrays are included whose actual array element type
is the result of upgrading element-type;
see Section 15.1.2.1 Array Upgrading.
If the dimension-spec is a rank,
the set includes only those arrays having that rank.
If the dimension-spec is a list of dimensions,
the set includes only those arrays having a rank
given by the length of the dimensions,
and having the indicated dimensions;
in this case, * matches any value for the corresponding dimension.
If the dimension-spec is the symbol *,
the set is not restricted on the basis of rank or dimension.
- See Also:
-
*print-array*,
aref,
make-array,
vector,
Section 2.4.8.12 Sharpsign A,
Section 22.1.3.8 Printing Other Arrays
- Notes:
-
Note that the type (array t)
is a proper subtype of the type (array *).
The reason is that the type (array t) is the set of arrays
that can
hold any object (the elements are of type t, which includes
all objects).
On the other hand, the type (array *)
is the set of all arrays whatsoever, including for example
arrays that can hold only characters.
The type (array character)
is not a subtype of the type (array t);
the two sets
are disjoint because the type (array character) is not the
set of all arrays that can hold
characters, but rather the set of
arrays
that are specialized to hold precisely characters and no
other objects.
- Allegro CL Implementation Details:
-
None.
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