CLHS: Function ARRAY-ELEMENT-TYPE

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Function ARRAY-ELEMENT-TYPE

Syntax:

array-element-type array => typespec

Arguments and Values:

array---an array.

typespec---a type specifier.

Description:

Returns a type specifier which represents the actual array element type of the array, which is the set of objects that such an array can hold. (Because of array upgrading, this type specifier can in some cases denote a supertype of the expressed array element type of the array.)

Examples:

     (array-element-type (make-array 4)) =>  T
     (array-element-type (make-array 12 :element-type '(unsigned-byte 8)))
    =>  implementation-dependent
     (array-element-type (make-array 12 :element-type '(unsigned-byte 5)))
    =>  implementation-dependent

     (array-element-type (make-array 5 :element-type '(mod 5)))

could be `(mod 5)`, `(mod 8)`, `fixnum`, `t`, or any other type of which `(mod 5)` is a subtype.

Affected By:

The implementation.

Exceptional Situations:

Should signal an error of type type-error if its argument is not an array.

See Also:

array, make-array, subtypep, upgraded-array-element-type

Notes: None.

The following X3J13 cleanup issue, not part of the specification, applies to this section:

- ARRAY-TYPE-ELEMENT-TYPE-SEMANTICS:UNIFY-UPGRADING

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