Substitutions in Common Lisp

Question

I’m trying to write a function with two arguments of this type:

substitutions (list_one, list_two)

list_one has always this form (letters can c

Answer 1

If the lists are proper you can iterate them with the loop macro and pop off the arguments in the accessible free variable:

(defun template-replace (template replacements)
  (labels ((iterate (template)
             (loop :for element :in template
                   :collect
                   (cond ((consp element) (iterate element))
                         ((symbolp element) (pop replacements))
                         (t element)))))
    (iterate template)))


(template-replace '(1 rep (4 rep (9 rep)) rep) '(foot inch mm multiplied))
; ==> (1 foot (4 inch (9 mm)) multiplied)