- Syntax:
-
typep
object type-specifier &optional environment
generalized-boolean
- Arguments and Values:
-
object - an object.
type-specifier - any type specifier except
values, or a type specifier list
whose first element is either function or values.
environment - an environment object.
The default is nil, denoting the null lexical environment
and the and current global environment.
generalized-boolean - a generalized boolean.
- Description:
-
Returns true if object is of the type specified by type-specifier; otherwise, returns false.
A type-specifier of the form (satisfies fn)
is handled by applying the function fn to object.
(typep object '(array type-specifier)),
where type-specifier is not *,
returns true if and only if object is an array
that could be the result
of supplying type-specifier
as the :element-type argument to make-array.
(array *) refers to all arrays
regardless of element type, while (array type-specifier)
refers only to those arrays
that can result from giving type-specifier as the
:element-type argument to make-array.
A similar interpretation applies to (simple-array type-specifier)
and (vector type-specifier).
See Section 15.1.2.1 Array Upgrading.
(typep object '(complex type-specifier))
returns true for all complex numbers that can result from
giving numbers of type type-specifier
to the function complex, plus all other complex numbers
of the same specialized representation.
Both the real and the imaginary parts of any such
complex number must satisfy:
(typep realpart 'type-specifier)
(typep imagpart 'type-specifier)
See the function upgraded-complex-part-type.
- Examples:
-
(typep 12 'integer) true
(typep (1+ most-positive-fixnum) 'fixnum) false
(typep nil t) true
(typep nil nil) false
(typep 1 '(mod 2)) true
(typep #c(1 1) '(complex (eql 1))) true
;; To understand this next example, you might need to refer to
;; Section 12.1.5.3 Rule of Canonical Representation for Complex Rationals.
(typep #c(0 0) '(complex (eql 0))) false
Let Ax and Ay be two type specifiers that
denote different types, but for which
(upgraded-array-element-type 'Ax)
and
(upgraded-array-element-type 'Ay)
denote the same type. Notice that
(typep (make-array 0 :element-type 'Ax) '(array Ax)) true
(typep (make-array 0 :element-type 'Ay) '(array Ay)) true
(typep (make-array 0 :element-type 'Ax) '(array Ay)) true
(typep (make-array 0 :element-type 'Ay) '(array Ax)) true
- Exceptional Situations:
-
An error of type error is signaled if type-specifier is values,
or a type specifier list whose first element is either
function or values.
The consequences are undefined if
the type-specifier is not a type specifier.
- See Also:
-
type-of,
upgraded-array-element-type,
upgraded-complex-part-type,
Section 4.2.3 Type Specifiers
- Notes:
-
Implementations are encouraged to recognize and optimize the case of
(typep x (the class y)),
since it does not involve any need for expansion
of deftype information at runtime.
- Allegro CL Implementation Details:
-
None.
4 Types and Classes