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- | ANSI Common Lisp 9 Conditions 9.1 Condition System Concepts 9.1.2 Creating Conditions ### 9.1.2.1 Condition Designators A number of the functions in the condition system take arguments which are identified as condition designators. By convention, those arguments are notated as datum `&rest` arguments Taken together, the datum and the arguments are "designators for a condition of default type default-type." How the denoted condition is computed depends on the type of the datum: If the datum is a symbol naming a condition type ... The denoted condition is the result of
       (apply #'make-condition datum arguments)
- If the datum is a format control ... The denoted condition is the result of
       (make-condition defaulted-type
                       :format-control datum
                       :format-arguments arguments)
where the defaulted-type is a subtype of default-type. If the datum is a condition ... The denoted condition is the datum itself. In this case, unless otherwise specified by the description of the operator in question, the arguments must be null; that is, the consequences are undefined if any arguments were supplied. Note that the default-type gets used only in the case where the datum string is supplied. In the other situations, the resulting condition is not necessarily of type default-type. Here are some illustrations of how different condition designators can denote equivalent condition objects:
    (let ((c (make-condition 'arithmetic-error :operator '/ :operands '(7 0))))
      (error c))
    ==(error 'arithmetic-error :operator '/ :operands '(7 0))

    (error "Bad luck.")
    ==(error 'simple-error :format-control "Bad luck." :format-arguments '())

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