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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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