If you put the aif code presented in onlisp in a package and try to use it in another you run in the problem that packagename:it is not external.

(in-package :packagename)

(defmacro aif (test-form then-form &optional else-form)
  ‘(let ((it ,test-form))
     (if it ,then-form ,else-form)))

wanted call syntax

(in-package :otherpackage)

(aif (do-stuff)
  (FORMAT t "~a~%" it)
  (FORMAT t "just got nil~%"))

How can I fix this behavior in code, without making the variable it external in the package declaration and beeing able to access it just by it instead of packagename:it?