Re: [Chicken-users] Anaphoric IF

[William Annis]

 >(if* (member x y) (cadr it) ...)
 >
 >(if* (assq x y) (cdr it) #f)
 >
   <snip>
 >
 >Pointless or practical?

        I do this all the time.  

;; Anaphoric varieties of these things.
(define-macro (if* test a-then a-else)
  `(let ((it ,test))
     (if it ,a-then ,a-else)))

;; Translated from "On Lisp" version by Paul Graham.
(define-macro (cond* . clauses)
  (if (null? clauses)
      #f
      (let ((cl1 (car clauses))
            (sym (gensym)))
        `(let ((,sym ,(car cl1)))
           (if ,sym
               (let ((it ,sym)) ,@(cdr cl1))
               (cond* ,@(cdr clauses)))))))

-- 
William Annis  -   System Administrator  -  Biomedical Computing Group
"No man forgets his original trade: the rights of nations and of kings sink
into questions of grammar, if grammarians discuss them." Samuel Johnson