aif_without_free_variables.scm

(define-syntax aif
  (sc-macro-transformer
    (lambda (form env)
	  `(let ((it ,(make-sc env '() pred)))
		 (aif* ,@(cddr form))))))

(define-syntax aif*
  (sc-macro-transformer
    (lambda (form env)
	  (let ((then (cadr form))
			(else (if (null? (cddr form)))
				  #f
				  (caddr form) ))
		`(if ,(make-sc env '() 'it)
			 ,(make-sc env '() then)
			 ,(make-sc env '() else))))))