typep object type-specifier &optional environment => generalized-boolean
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.
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 184.108.40.206 (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.
(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 220.127.116.11 (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 '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
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.
type-of, upgraded-array-element-type, upgraded-complex-part-type,
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.