#!/usr/local/bin/sbcl --script

(defmacro -> (form &rest forms)
  (if (null forms)
      form
    (let ((git (intern (symbol-name '#:it))))
      `(let ((,git ,form)) (-> ,@forms)))))

(defun square (n)
  (* n n))

(defun add1 (n)
  (1+ n))

(defun macroexpand-all (form &optional environment)
  (let ((sb-walker::*walk-form-expand-macros-p* t))
    (sb-walker:walk-form
     form environment
     (lambda (subform context env)
       (acond ((and (eq context :eval)
                    (listp subform)
                    (symbolp (car subform))
                    (get (car subform) :partial-macroexpander))
               ;; The partial expander must return T as its second value
               ;; if it wants to stop the walk.
               (funcall it subform env))
              (t
               subform))))))

(princ (macroexpand-all '(-> 5 (add1 it) (square it))))