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| ANSI Common Lisp 5 Data and Control Flow 5.3 Dictionary of Data and Control Flow
5.3.43 if | Special Operator
  Syntax: if test-form then-form [else-form] {result}* Arguments and Values: Test-form - a form. Then-form - a form. Else-form - a form. The default is nil. results - if the test-form yielded true, the values returned by the then-form; otherwise, the values returned by the else-form. Description: if allows the execution of a form to be dependent on a single test-form. First test-form is evaluated. If the result is true, then then-form is selected; otherwise else-form is selected. Whichever form is selected is then evaluated. Examples:
       (if t 1)  1
       (if nil 1 2)  2
       (defun test ()
         (dolist (truth-value '(t nil 1 (a b c)))
           (if truth-value (print 'true) (print 'false))
           (prin1 truth-value)))   TEST
       (test)
       TRUE T
       FALSE NIL
       TRUE 1
       TRUE (A B C)
        NIL
  See Also: cond, unless, when Notes:
       (if test-form then-form else-form)
       ==(cond (test-form then-form) (t else-form))
Allegro CL Implementation Details: None.

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