lispdoc - results for check-type

(check-type place type &optional type-string &environment env)
Function: Signal a restartable error of type TYPE-ERROR if the value of PLACE is not of the specified type. If an error is signalled and the restart is used to return, this can only return if the STORE-VALUE restart is invoked. In that case it will store into PLACE and start over.
(defun sqr (x)
  "Multiply x by itself."
  (check-type x number)
  (* x x))
Mentioned in:
CLtL2 - 24.1. General Error-Signaling Functions
CLtL2 - 24.2. Specialized Error-Signaling Forms and Macros
CLtL2 - 29.4.1. Signaling Conditions
CLtL2 - 29.4.2. Assertions
CLtL2 - 29.5. Predefined Condition Types
CLtL2 - 7.2. Generalized Variables
HyperSpec - Macro CHECK-TYPE