Iter through macroexpand-dammit

  (defmacro iter (&body body)
    (with-gensyms (iter-block accumulate start)
      (handler-case
          (macroexpand-dammit:macroexpand-dammit
            `(block ,iter-block
               (let ((,accumulate nil))
                 (macrolet ((while (condition)
                              `(unless ,condition
                                 (return-from ,',iter-block
                                   (nreverse ,',accumulate))))
                            (collect (thing &key into)
                              (if into
                                  (signal 'accumulate-target :name into)
                                 `(push ,thing ,',accumulate))))
                    (tagbody
                      ,start
                      ,@body
                      (go ,start))))))
         ;; handler
         (accumulate-target (c)
           (setf accumulate (name c))
           (macroexpand-dammit:macroexpand-dammit
             `(block ,iter-block
                (let ((,accumulate nil))
                   (macrolet ((while (condition)
                                `(unless ,condition
                                    (return-from ,',iter-block
                                      (nreverse ,',accumulate))))
                              (collect (thing &key into)
                                `(push ,thing ,',accumulate)))
                      (tagbody
                        ,start
                        ,@body
                        (go ,start))))))))))

CL-USER> (let ((i 0))
           (iter (while (< i 5))
                 (incf i)
                 (print acc)
                 (collect (+ 3 (* 4 i)) :into acc)))
NIL 
(7) 
(11 7) 
(15 11 7) 
(19 15 11 7) 
(7 11 15 19 23) ; This is the return value, everything above was printed.